Hi
What do you have installed on the computer right now?
If you aren't running more the 3 gigabytes of ram it would be simpler to just run 32 bit Windows 7.
Do you know if there are any Windows 7 specific 32 bit drivers for your software?
I suppose that it's not a sure thing that the drivers will work in Windows 7 32 bit, but I would expect them to.
I've never run across anything that would run in Windows XP that wouldn't run in Windows 7 32 bit.
If you already have Windows 7 64 Ultimate installed then I'd try the Virtual XP, I've never done this myself so my experience is limited on how all of that works.
Mike