Notice: I am not a computer tech. I am just a droog who uses computers a lot for my droogy shenanigans and of course for audio purposes. The following is mostly anecdotal and cobbled together from experience and scattered online research. If you want pro advice there are companies that can help you tweak your system(s) for audio for modest fees.
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A newer, more powerful machine will certainly help but if it is coming with a factory install of Windows and prepackaged software (bloatware, nuisance trial AVs, Windows pre-config'd for "general" consumer usage, etc) you are gonna want to do some serious cleanup of the system.
You have two options in this regard both of which are a massive PITA. You may be aware of this but maybe not and it might be interesting/helpful to others in the same predicament.
1) Do a completely fresh install of Windows. Not sure what the manufacturers are including with pre-built systems these days but it'll likely be Win 8.1 or perhaps Win 10 (but I think that's still a pre-release). You will be getting a Windows license either way which will be printed on a sticker somewhere on the system (which you probably know). With that you can use any disc or download copy of the SAME version of Windows (so you'll likely be stuck with Win 8.1). Unfortunately I have not yet seen Microsoft release an online download for clean copies of Win 8 on their download site Digital River. They have Win7 though so I, as a Win 7 user on both of my machines can use those downloads and for my laptop install just using the license key from the sticker on the bottom to get a fresh install or for my DAW, which I built myself from scratch, I can use the license from the OEM disc I bought (but it's unnecessary for the DAW because I actually have the disc... the reason I can't use that same disc on my laptop is because it came with Win7 Home and the disc I bought for my DAW is Win7 Pro. You can't use a Pro disc to install with a Home license or vice versa. Same with Ultimate. Gotta be the exact same version of Windows).
So unless you can borrow a Win8 disc from somewhere (or find a clean download but I would NOT trust an OS coming from the internet unless it was released by Microsoft themselves) you would have to buy a copy of Win8. Microsoft however are also going to be giving away free upgrades to Win10 to licensed Win7 and 8 users for a year. Not sure if that is for just an "upgrade" version (which is not advisable... you'll want a clean install with a full copy) or if they'll let us download a full version to completely overwrite our old installs. Either way that could be an option but I digress...
The point is you need a clean copy of Windows and a license key. However you get it or work it that's what's gotta happen.
The benefits of a clean install are obvious. You don't have ANY extra bloatware or crap to remove or worry about screwing things up in the background (like phoning home, hogging resources, changing your settings, starting up at weird times, etc...). A lot of those preinstalled systems come with "helpful" system applications that scurry around trying to do crap that for most users might be helpful (because they aren't doing anything that requires the system to FOCUS on stuff like streaming audio/video). Never mind all the bloatware and useless antiviruses that are almost worst than an actual virus themseleves.
You do however have to do a pile of crap to set the system up and unless you know a bit about computers it's going to be daunting. Before you do ANYTHING though follow the initial startup instructions for the system which will usually tell you how to create a system image. Many of these prebuilt comps have a dedicated partition that houses a recovery file/utility so you can go back to factory default at any time (and don't wipe that out when doing the drive partioning/clean Windows install) but you'll also want a back up... on disc or an external drive or preferably both... just to be safe.
Most importantly for a clean install is finding, downloading and installing ALL the necessary drivers for the hardware on your system. This would be drivers for the motherboard, video and onboard soundcard(s), USB and other port drivers and various other components. A lot of this stuff will be on the system manufacturer's website (if you bought something like a Dell or an ASUS just search the model number of the system and it should give you some download links... if it's a custom dealie then you may have to find out exactly what is in the system then scout the model numbers on the sites of the manufacturers who made the components... which is what I had to do because I built my own system). If you are on a site like Acer's or Dell's or HP's or whatever looking for drivers there'll likely be a bunch of utilities as well. Some of those are useful and critical... others are not and actually cause problems. Look up exactly what things do before you install them and only install the bare minimum. If you start running into problems take another look at what you didn't install to see if maybe they'll help fix it.
As you can see this is already getting to be a massive PITA. I've done it and it sucks and sometimes it can take a while to really get everything you need on the system. As I do this I generally create tons of restore points and images to return back to. Like once I get Windows installed (which takes FOREVER) I'll create a restore point. Then I'll add all the drivers for the system and create another restore point or maybe an image (this way I can go back if I install something dumb or if I want to use the system for a couple days THEN go back to a clean install to continue adding stuff I can... because just the winows and driver install can take most of an afternoon). Then I'll start adding crcuial programs like Antiviruses and set up my preferred web browser with the correct settings and go through the Windows system settings I like and create another restore point or preferably image. At that point I have a clean system with all the CRUCIAL stuff I like and I can return to that. That's my main image and if something goes funky it's WAY better than spending another whole day reinstalling everything. BTW as you get the drivers and all that it's convenient to put them all on a setup disc or in a back up folder so if you want to do it all over again you don't have to download everything from scratch (which is where a lot of time is wasted).
From there I start putting more "frivolous" stuff that I like to use like my audio software and device drivers (for interfaces, MIDI stuff, games, graphic/text editors, media players, etc). Because I've been creating images/restore points I can go back to any stage of all this to ensure I'm going back to a clean system (so if I've picked up any viruses or something wonky has happened while I screwed around on the system it goes away). At that point I've got a clean system, set up properly and securely WITH the stuff I actually use my computer for. I can then create an image of that and save myself an arseload of time in the future if I need to restore without too much disruption to my day to day useage.
This constant back and forth and layering of settings/programs can take a VERY long time. Most guys will probably laugh at all that and really it's not all that necessary to be such a spazz but to me it's catastrophe protection and really... I find just wiping and restoring a system using a good, well thought out, recovery point is very useful/comforting. I don't use crazy back up utilities or anything like that. It's all manually done using the windows utilities (but I have made Acronis back ups for other stuff).
So yeah... does that sound like fun? Probably not but using the general principles of that method gets you a clean system and you don't have annoying and stubborn programs entrenched on the system.
The serious downside is sometimes, especially on a laptop, the manufacturer has done and/or installed things to make the system work better that cannot be duplicated by the end user. On my laptop (Acer) I actually did the method above a couple times and fiddled and fiddled and fiddled and many things worked WAY better with the clean install and the computer was less annoying in most regards BUT the hardware did some weird crap (like my drives would spin up then down every 10 seconds or so for no reason which was audibly annoying and likely bad for them). Desktops should not suffer that type of crap as much but who knows what these clowns put into their systems.
So the other option is....
2) Use the preinstalled version of Windows and go nuclear holocaust on ALL the useless crap the manufacturer installed. With this method the only thing you install are driver updates (be sure to check for all available updates for all the components of your system which are usually available on the manufacturer's website but you may need to go the component's manus websites as well) and replacing crucial programs that you remove (like antivirus software).
BTW... make sure to backup the factory restore point as soon as you turn on the computer. That way you can return to a factory state even your hardrive totally craps out. Seems weird to keep a back up of something that sucks and you are about to completely destroy but if you screw up or something weird happens or maybe you want to sell the system that's the original state of the computer. Fresh slate and all that.
The first thing that needs to go and be replaced is usually the AntiVirus software. If it's a DAW you want a lightweight, non intrusive AV like Microsoft Security Essentials. I don't use that on my surfing machines because although it is a good AV I don't trust it as much as others... but it is less intrusive to audio. So just don't search for goat porn or do dumb stuff on your DAW and MSE should be more than fine. I never keep my DAW online except to snag audio related programs/updates or do stuff on secure and trusted site.
Those McAffee or Norton trials that come preinstalled are super intrusive and WILL screw with your audio. They aren't really very good AVs anyway compared to others so once you get MSE downloaded disconnect you system from the internet and remove the included AV and install MSE.
Then download and install Piriform's CCleaner (which is what I use) or I've heard good things about Revo Uninstaller (but haven't tried it yet). These programs serve multiple functions but the one thing they are needed for in this instance is getting rid of stubborn bloatware. In my experience most programs will mostly uninstall just using their own uninstallers or using the Windows uninstall option but some simply WILL NOT GO AWAY without a more agressive and through tool like CCleaner. And even still when using the provided uninstallers for many programs tons of residue from the program gets left behind as well as fragmented areas on disk where those programs used to live. I've even had programs that I had uninstalled continue to harass me to reinstall or download "the letest greatest version"... no. Not cool at all and the fact that system resources are being dedicated to that kind of crap after I specifically removed the program is infuriating.
So I usually do a few passes when I'm uninstalling. The first is to get rid of compeltely obvious nonsense like dumb programs that automatically link to online store or whatever (like on my laptop there is Acer Games online or some such nonsense... GONE). Really anything that is unnecessary and/or tries to call home or sell you crap is ripe for nukination. Then I'll go through and figure out which of the "useful" programs included are trials. There are usually a bunch of these that once you open them you relaize it's a 30 day trial or a crippled version and they'll just nag at you and collect info or whatever... GONE! Then I'll get a little more selective and start googling the more obscure, less obviously program entries. If it's a crucial program that helps the system function it'll stay. If it's some sneaky bullpuck nonsense it goes.
After I feel like I've yanked the large majority of bloatware out then I'll use CCleaner to clean up the registry, defrag, etc. The system usually works a LOT faster at that point.
Then I'll move on to system settings in the Windows Control panel. All these preinstall systems have everything set to save power which is no good for audio. Go into the control panel and make sure all your drives, ports (USB especially) and anything else is set to "Always On", "Max" or whatever will make it so things aren't falling asleep on you. You can kind of do this by just choosing the Performance option in the general Power Management section but I prefer to use the Advanced option and go through everything one component at a time to make sure.
Then you want to disable all unnecessary Start Up programs (you'll want your AV to stay on and that can be an issue but if you are connected to the internet leave it... however there may be other crap in there that serves YOU no purpose). The Task Manager would be another place to look to make sure there aren't scheduled tasks (like bloatware programs calling home or whatever). Set your internet security settings to lock the system down like a drum (so random flotsam/jetsam isn't coming to and fro from the system). Set Win updates to manual so you don;t start auto downloading/installing while doing audio (but remember to check for updates).
Really just look for anything that might distract the system.
Another note on antiviruses. I turn the real time protection off on my DAW unless I'm online because it really does slow down load times and does screwy crap when calling up or manipulating data from disk (it constantly tries to scan the files)... BUT the way around this is to learn how to use the Whitelist within your chosen AV. If you add your Cakewalk project/audio/content/VST folders or anything that might be being used for audio (that you trust and have personally installed) and add it to your whitelist then it should improve performance.
Anyhoo... that's a lot of typing but I guess I was feeling fingery. I am not a tech but I am always at a computer and always poking at my DAW so I guess at this point I have a laymen's impression of what works and what doesn't.
Might be helpful to you or someone or I could be a moron. Either way that's how I do things to circumvent all the useless crap vendors cram down our throats.
Cheers.