My question is that I have a Dell Inspiron 530 (fat) w/ Core 2 Quad 9300 that I've done a few minor upgrades to and I'm quite happy with it. My question is, I would like to run Windows 7 Ultimate 64 bit & Windows XP Professional on the same computer. I have the stock 350 watt power supply and it seems to be working just fine with the upgraded ATI 5670 from Sapphire. Would it be better to have a 1 TB hard drive partition and run both OS's on the same hard drive or simply install the OS's on separate hard drives. One 1 TB hard drive and another 500 GB hard drive. Both have 7200 RPM, the 500 GB is 16 MB Cache, 1 TB is 32 MB Cache. My concern is heat. With one drive heat is easily dissipated, with 2 it runs a little warm. Would 2 hard drive prove added performance with an extra or would the performance gain be minimal at best. I'm interested in performance and longevity equally. Not a gaming rig for the most part. I'm looking at doing some AutoCAD stuff here soon.
Have you considered running XP under a VM? Which OS do you do the autocad from, and what apps do you need XP for?
If you truly need a dual boot, and you have enough space, there's no technical reason you can't do it from 1 HD with a partition. I don't know enough about AC to know how much disk access is an issue, vs. processor & video card. There COULD be an argument for 2 HDs if you have something disk intensive, you could separate that out from OS/swap physical drive.