do i need a separate machine for the internet?

No. Running a DAW on the internet is fine- also makes it easy to updates plugins and the DAW itself.

No real reason to have a dedicated internet PC. Just make sure to take the normal AV and firewall precautions when on the internet.

I think you'll find a few schools of thought on this question.  IMHO, I believe it comes down to how critical your DAW is and how much you want to deal with potential resource issues or software conflicts, etc.

If you make your living on your DAW and need to minimize downtime and maximize performance, then you'll likely want to separate your DAW from your general PC.

Conversely, if you're a hobbyist who's income isn't affected if you had an issue once in a while and aren't stretching your system's performance limits by DAW projects with lots of soft synths & effects, then you can likely combine your DAW and home PC together if you have a very powerful PC and don't mind doing some troubleshooting once in a while.

FWIW, I have my DAW separate from my home PC, even though I"m just a hobbyist.  My home PC has so many background services running from installed apps and receives frequent application / OS updates  that I don't want to deal with the hassle of potential resource issues on large DAW projects. 

Nothing's definite though - you may combine the two and never have a single issue - but the more pieces of software you have on a single machine increases the liklihood of an issue at some point. But you may feel differently.  YMMV.

Hope that helps
Russ
  

One thing I forgot to mention, when my DAW was on my desktop, I set it up to dual boot. One boot was for my "office" based stuff and the t'other one was for my DAW.

I still connected both boot sessions to the interweb, but my DAW boot had music only software on it, and I cut down the number of process down quite considerably.

I earn my living with music.  This includes using my DAW.
 
If I have clients in I will not go on internet whilst tracking, and will disable my AV.  I've not had problems with either, but better safe than sorry.

 Hello again and Thanks,
you guys are great.
i'm pretty serious about my projects,but ultimately,
i don't generate an income from it(and don't anticipate
it either).
so, while it would be nice to have a replacement,i suppose
i'll hold off for the moment.
i tend to keep my projects small anyway,5 or 6 tracks and
then i bounce.
Thanks Again  m.r.

Having your DAW on a network has many advantages, from ease of authorizing plugins to convenient project backups to a file server. 

However, network adapters, drivers and associated software are responsible for most of the CPU and I/O overhead that limits your DAW's efficiency and system latency. If you're on the internet you need firewalls and antivirus protection, which impose additional overhead. Network adapters assume that they are the most important components in your computer and that servicing network traffic should take priority over everything else, including audio. Wireless adapters in particular are horribly inefficient.

The solution: set up a way to disable the network while you're doing audio work, and to re-enable it when needed. Hardware profiles are one way to go, but may require a reboot to switch from one mode to another. Another approach is to create a batch file that turns the network off and shuts down unneeded processes. This method allows you to easily switch between dedicated DAW and general-purpose networked machine, for the best of both worlds.

For years I went to a dual boot but 1 computer. Both boots were connected to the internet but the DAW boot was not used for general browsing.

The biggest problem I found was not the internet but other programs that like to add services and background processes and make tweaks to the system without telling me.

My current DAW is a dedicated machine connected to the network but not used for browsing. I have dual DVI output and a dual DVI switch so I can easily flip from one computer to the next. I did find it better to use a different mouse and keyboard for each computer, but they share the same dual output widescreens.

I don't work with clients and use Sonar for my own stuff - CD releases and backing tracks.  Personally I like the Dual Boot approach, one stripped down for DAW use and one for general purpose use.  Both have Sonar available.  Typically i use the DAW side when I am creating new projects and recording actual audio.  For editing / exporting / and live work (I use the matrix at times) I use the general purpose boot.  Both boots share a common folder structure.  I do have an internet connection on the DAW side, but I only use it for updates to Sonar and Plugins - Although most times I download from the general purpose side and place files on a common drive.


Cheers

Grif

All I can say is that I somehow picked up very ugly viruses on two separate occassions without engaging in any obviously unsafe Internet practices.  (I suspect one was picked up from Facebook.  The other one started immediately after I tried to update iTunes.)

I picked these up even though I was running up-to-date virus protection (WebRoot).

These viruses required completely rebuilding my machine which meant reinstalling all software and drivers, reconfiguring everything, and going through enormous pain to get back to where I was.  I lost all my Melodyne edits on an album when I reinstalled Melodyne.  The V-Studio interface set-up was completely wrecked and it took some time to get that right.  It was ten days before I was operating, and it was only weeks later that I finally got the last of the VSTs reinstalled and back as they were.  A lot of project work had to be redone.

I now connect my music PC to the Internet only to download, authorize, or update music software or to publish music to the Internet.  I bought the cheapest laptop I could find at BestBuy ($400) for email, Facebook, iTunes/etc. and I use either the laptop or an iPhone for all non-music Internet stuff.

It's up to you, but that is my experience.

I am going to have to disagree a bit with some things that have been said.  I got viruses without downloading and running something.  One week after my PC technician told me it was not easy to get a virus, he got one on his studio machine and spent a week rebuilding.

I am not trying to scare anyone, but I do recommend caution.  There have been some pretty destructive things on Facebook, for example.

Didn't read through everything but a simple solution is to use VMware player to create a virt machine that you use for internet only. Create a virt C and D drive, make the C drive your system and unwritable. Save files to the D drive and copy/paste between systems when needed. The VMware player will put negligible load on your system when you don't have an active session (though I run mine and my DAW at the same time often with no ill effects).... 

edit - I use vmware but there are also plenty of other options (free and paid).

I always found that when I did the dual boot thing I ignored my DAW so vmware was a good compromise. Takes 10-20 secs to boot XP under win 8, I leave it up and if it causes me problems while running Sonar I shut it down for however long needed. Another good thing is that with the read only C drive it doesn't matter if you get a virus so no anti-virus sw required, if you do get a virus just reboot and its gone.