Some programs I need don't run under Windows 7.
Virtual XP is your friend. I coordinated and executed a whole migration from XP to Windows 7 at the office I work at, and despite the mess of proprietary software we use, there was only ONE piece of software that ONE person uses, that wasn't compatible with Windows 7. We later found their newest version works, we just need to get the new version (a 0.1 version update). Long story short:
bullshit, you haven't even tried, have you?
I'm not sure what you mean by this. I can run two GPUs just fine.
What I mean is pretty simple: XP DOES NOT SUPPORT MODERN GPU ARCHITECTURE. It's well-established that GPU-compute technologies are specific to Windows Vista's WDDM (Windows Display Driver Model) architecture, something that's not present at all in Windows XP. XP has to use a bunch of hacks to even allow modern GPUs/CPUs to operate, and far from "efficiently".
But hey, if you can "run two GPUs just fine", why are you even posting here?
I'm not even close to kidding here. Stop torturing your Sandy Bridge-based PC with the slums of Windows XP. It'll treat you a lot better if you run it within its design parameters, and put a modern OS on the thing that supports its amazing new technologies. XP is a compatibility-mode hack on your system. An insult. It honestly makes me physically ill to think about how badly the thing is abused while running XP...