Vista is out. I actually have a copy as its free to download for all students and staff in the CS department who join Academic Alliance (and I imagine the entire University but don't quote me on that), but I've yet to install it for fear that it will replace my unlicensed and unkeyed whiny Windows XP with an OS that is fully legit but no longer speaks to my wireless adaptor, USB devices, soundcard or graphics card. Or more worryingly that it will work perfectly at an initial glance but some insidious problems will bubble to the surface.
Maybe when the Family edition comes out on Academic Alliance I'll dabble. I've played around and like what I saw, though there seems little tangible benefit in upgrading other than a pretty desktop.
So for now my expert? advice is to follow this guy:-