Welcome
I'll take into consideration that you're a new forumer. so anyways XP for now is better, with vista you might have some probs like wireless,Audio drivers.etc but anyways it all depends on the hardware you have if vista supports it.
its better to wait until vista has its official service pack release then install it.
stick to XP for now, but if you want to , you can go vista only then will you know what hardware or software works with.
but then again thats my personal opinion!! others may differ
Patrickv