Vista sucks, you can barely run it on less then 2gb of memory and it's annoying as hell to be asked "are you sure you really want to do that", "allow" anytme you want to do something. I can't stand Vista, it's like they dumbed down XP and make every action take twice and many clicks to get where you want to go and even after upgrading memory on my laptop you can't do multiple applications without freezing, it takes 6/7 minutes to reboot and crashed multiple times daily.
I have a 3 year old XP desktop with the similar specs, it's fast as hell and hasn't crashed once.