John
I am very happy with Windows 8 and X3.  I do think its smart to go with the most current OS however, I don't think choosing Windows 7 is a poor choice just not a smart one. 

The good thing about forums is that you get a wide variety of opinions.  The bad is that you have to filter out the rubbish information from the good & even at times, take things with "a pinch of salt" otherwise you may never do what you intended to do!
 
While I agree with some of John's statement, I don't agree with the statement that "it's smart to go with the most current OS".
 
The one thing that history has taught us is that installing the latest piece of software is definitely not smart as there are inevitably bugs in there which may or may not be encountered so you're playing "Russian Roulette" when you install a brand new piece of software.  History has taught us that in fact the smart thing to do is wait for about 6 months for all the "smart Alex's" of the World to use the software & find the remaining bugs & install the software after the first update.
 
Hence why we find that Microsoft are about to release Windows 8.1!  Hence why Sonar X3 is already on revision A & shortly will be updated to B!
 
Then there are other issues like the fact that some hardware vendors are NOT quick to update their drivers to run with the newest & latest OS.  I've seen lots of posts where people have upgraded OS then realised that their hardware isn't supported on that OS.  So installing the latest OS without checking that you have all the correct drivers is neither smart or wise.  Some users also say, it's fine as I'll install the Windows 7 drivers under Windows 8!  While this may work sometimes, this can also cause system instability & is one of the main reasons Windows becomes unstable & you get the BSOD (wrong or incompatible drivers).
 
However, once the software has bedded down, then I agree with John as it's likely that the most current software has been enhanced & optimised to run with each other so in that context, it is a smart move.
 
If you look at the technical testing which has been done, there is no denying that Windows 8 runs more efficiently & is quicker in almost everything it does compared to Windows Vista & 7!  We've tested configurations where I work so I've seen the difference but it's hardly surprising as they got rid of the Aero interface which was a huge overhead on the OS.  By comparison you should see how quick & efficient Windows Server 2008 R2 runs!  Why, because it's basically Windows 7 with all the consumer rubbish & Aero removed.  Funny that...
 
Personally, my new rig has Windows 7 pro 64-bit which I'm sticking with for a while as I'm not a huge fan of that thing formally called Metro & also don't agree with Microsoft's current vision which was to install a mobile focused OS on a desktop computer.  Mobile & desktop computing should have some differences as what is happening now is that consumers are moving to mobile devices like smart phones & tablets whereas the desktop market is becoming for specialist groups or power users, as it was in the early days before computing desktops became mainstream.
 
As a specialist/power user, I want a full desktop experience & I don't want to use something which looks like two GUIs which have been badly implemented.  That Metro thing doesn't work seamlessly with what's left as a desktop experience with a ridiculous "Lego land" style interface sliding across my screen like a portcullis every time I go to launch a program.  And those apps are just rubbish as they're more or less stuck in a fixed resolution & they don't multitask properly so what's the point of it running on a powerful desktop computer which begs for a full multitasking environment?
 
Don't get me wrong, on a phone, tablet or any other mobile device, I get it & I'm with them!
 
So it is on this basis that I think there needs to be some distinction between a mobile OS & a full desktop experience just like Apple do with IOS for mobile devices & their MAC range of computers.
 
Microsoft are only running scarred because they want to ensure that Windows doesn't become irrelevant in the future in what's becoming a mobile computing world & I think they're going about it the wrong way as they're alienating power/specialist desktop users.

Thanks JimmyBoy for the url!  RickJP909, Wow!  Much appreciated! 

Thanks to all for this very useful information.

I recently bought a new PC that came with Windows 8.  never used Win8 at all fore this new PC.  I have used almost every other version of Windows.
 
After 4 hours playing with Win8 and many tears, real frustration and general screaming to the gods "I can't take this much change all at once!!!"  I gave up.
 
I returned the PC and bought a PC with win 7 pro 64bit.  X3 was a breeze to install and worked no problems.
 
Try Win8 before you take the plunge - you might be stuck with it and if it doesn't work for you, then you might be frustrated and feel the pain.  or you may love it and it won't be an issue for you.  but try before you buy.

You should have come here and asked about it. There is an easy way to make the transition with Classic 8 start menu or Start 8. 
 
I boot directly to my desktop. I only goto metro if I want to run an app or start a program for the desktop that is not on the taskbar.  I could also use the Classic 8 menu system too. 
 
BTW Windows 8 still starts up very quickly. 
 
 

I'm not knock win 8 at all.  It's really fast and I have seen others fly threw things.
 
For ME it was too much fluff and no substance.  So Different, soooo sooo different than any other windows OS.  I'm sure with a book and a bunch of time on my hands I could figure out Win8.  It was such a horrible experience for ME.  I couldn't find notepad, etc etc.  Funny at one point I threw a CD into the drive, something popped up on the screen and then disappeared and for 10 minutes I was screaming (really!!) screaming at the machine "where is the CD!!!!, how do you access this stupid thing!!!!????, oh come'on where is the CD!!??..."  I kept getting London time widget popping (I'm in Colorado and couldn't change it) up and the nasdaq stock widget popping up.   Just my experience.  I'm getting older and too much change all at once is like a two by four to the head is overwhelming.
 
X3 is enough of a learning curve that for ME I would rather spend my time and resources learning X3 than how to access notepad all over again LOL.
 
I'm just putting it out there if OP is buying a new computer it may be something that they want to consider when making an investment, how much time they have, what the learning curve is going to be.  No biggy.

To find anything you simply type its name. Of all the Windows 8 is very easy to learn and understand. There is no fluff in it either.

I would check what drivers are available for any hardware you use before deciding.

That is a very good point Paulo. I was lucky that all my gear has Win 8 drivers. 

John
You should have come here and asked about it. There is an easy way to make the transition with Classic 8 start menu or Start 8. 
 
I boot directly to my desktop. I only goto metro if I want to run an app or start a program for the desktop that is not on the taskbar.  I could also use the Classic 8 menu system too. 
 
BTW Windows 8 still starts up very quickly.

Hi John.  I'm aware of the 3rd party utilities but that defeats the object of what Microsoft wanted.  A friends Dad bought a PC with Windows 8 & like several users on here, couldn't get to grips with it so we had to put Start 8 on it.  Now he's happier but getting to some control panel options & other low level areas is far more difficult & requires more key presses than any other previous MS OS!
 
And you're right that a quicker & easier way to use Windows 8 is by typing what you want but all this is a complete change from the way that previous Windows versions were designed as when MS introduced Windows 95 which was a radical change, MS stated a couple of things; basically the keyboard was dead as the mouse was quicker & the Start Menu was the future.  Now after almost two decades, they want everyone to forget that & change how users work with their desktops.
 
I agree with you regarding the performance & I mentioned this in my post but a really easy way to get Windows 8 performance from Windows 7 is to replace your system drive with an SSD!  We tried some experimentation at my work place & any OS boots in seconds, even Win XP!
 
I still stand by what I said though.  Microsoft took a gamble & it back fired so much that several major things have happened;
 
Windows 8.1 has arrived & guess what, the Start Button is back & you can boot straight to the desktop & you can't do either without a 3rd party utility in just plain 8!
 
Also, Steve Ballmer is leaving MS & he's the one who said that the traditional Start Menu/button desktop had to go!  Looks like he's the one who's going as MS have u-turned on all of that.
 
All I'm saying is that any prospective Windows 8 users beware before you leap, make sure about drivers & that you're comfortable with the new way it works.
 
Apart from the GUI which as you said with 3rd party utilities is changeable, I think the performance is improved but that's been at the expense of Aero which I actually liked & I think it looked better than that flat retro style they have now as I think that'll date even quicker & I don't think it looks as sleek - just my personal taste though!