Try the reinstall gamma. I have vista running on a laptop that initially had 1G(1.5 now) ram and when I reinstalled, it worked great.
I know some still love xp but I like the way when something crashes in vista, on the rare instance it actually happens, I can just kill the task and move on. So many times in xp, you have to restart. Hell if media player does not like something it can force you to restart!
Save your data and try it. You have nothing to lose.