I would go so far as to say that I think Windows 7 (64-bit) is MORE stable than XP. The thing about XP was (past tense, for me) that it worked pretty much all the time, BUT, I had a number of times when something (as a whole) locked up the system and I could not kill it to get the system back: REBOOT. Did not happen very often, but on more than one machine and when it did it sucked. In W7 that does not happen, or I have yet to experience it. (And I use W7 64-bit at home and at work, on several machines at both places.)
Also, what is really cool, is that W7 contains pretty much all device drivers built-in (not third party, but Microsoft’s) which basically makes many (not all, of course, and especially not specialized) devices compatible out-of-the-box.
Anyways, just my two cents… 