3 PC's in one - 3 OS' or one?

Thanks to the economy, lack of jobs and financial institutions taking all my money, I'm WAY behind the times with my computers (the newest is over five years old!).  I used to try and keep my PC's separate for their tasks for many reasons and have one for work/personal, one for gaming and, of course, one for the music studio (last at SONAR Producer 4).  Needless to say, all of these need to be upgraded but due to that first sentence I won't be able to afford to do all three.  Actually, let's put the gaming PC off for now as well (it's not as important as you approach 50 ;-)
 
The work PC needs to be pretty beefy to handle things like 3D Modeling (AutoCAD, Inventor, etc.), large photo editing and my wild 35mb spreadsheets.  Hopefully it will also be fast enough to run iTunes (pun intended for those who have large music libraries ;-)
Needless to say, if I'm already going to have to spend some money for this, I'm considering combining all usage into one PC - i.e., spending a lot on one box instead of compromising on multiple boxes.
 
I see two ways of doing this:  1) Try to run everything from the normal boot drive, or 2) Have multiple boot drives and select which one to use during bootup.
 
Currently I'm leaning toward the second option because I'd prefer to keep the environments separate (plus disk space is finally cheap so I can have separate hard drives for each usage).
 
What I'm wondering is if there are any pros or cons to this approach.  I realize that there might be some hardware issues, but I don't think these would be a reason to go with option 1.  What do you guys think?
 
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Separate thought...  Since there are always so many "What PC should I get to run the latest version of SONAR?" type questions, what about having a sticky thread that details the minimum requirements, the recommended requirements as well as a list of what's NOT necessary (including things like hardware and OS processes, etc.).  That way the general inquiries are handled.

Unless you plan to pay Microsoft for three licenses, you would be well advised to just use one system on one boot drive.

No, you only need ONE OS if you going to run WINDOWS. Windows 7 x64.
If you need a second OS it would be LINUX but I doubt you have any need of that?


By the way Auto Cad are in x64. You want definitely run Windows 7 X64 if you working with CAD.

Before you do anything, check the compatibility of the "old" software you have.  Some may not be Win 7 compatible.

Also check the hardware compatibility BEFORE doing any actual Win 7 install.  Some older hardware does not have Win 7 or at a minimum Vista drivers and will not work.  Older ADI198X (Soundmax) integrated audio is one that is NOT compatible. 

Microsoft has a Win 7 Upgrade Advisor  Click Me  and you should run that to see what is and isn't compatible
One response notes "Spybot".  I would advise using Malwarebytes for malware/spyware scanner over Spybot.  I had to "clean" a client's PC recently that had malware on it.  I ran Spybot and it didn't detect any problems.  I ran Malwarebytes and it found the problem malware plus 4 other spyware/malware items and allowed me to get rid of all of them and save having to reformat and reinstall for the client.
 

zgraf

I like the multi-boot option, as it effectively isolates each environment from the others.

Me too.  My previous setup consisted of a dual-boot PC with 2 installations of Windows XP.  Boot1 functioned as the family computer whereas Boot2 was DAW only.  Boot2 was a lean installation with only Sonar and plug-ins installed (plus a few essential pieces of other music-related software).  It had no internet connection, no virus protection or firewall and fewer background services were running.  All unnecessary hardware such as printer and scanner were disabled.

Sonar was installed on both boots and it ran noticably better on Boot2.  Projects would load in a fraction of the time.

Been there, but didn't see any non-audio or video type PC's offered.  The reason I thought I'd ask is that I also don't know of any place to buy a pre-overclocked PC that's been made stable before I get it.  Scott's done far more work on determining the best and most stable configurations so I was curious if he does the same for basic work PC's too.