Windows XP or Windows Vista ?

No i think xp is best

i prefer to windows vista beacuse i think now i feel boring to use windows xp i m doing wait for vista pack i will get it soon

Too early to say yet. I will wait for Vista Service Pack 1 to come out before changing. I tried XP Pro 64 bit the other day and immediatly ran into problems with drivers. Windows doesn't write drivers, the component manufacturers have to write them and if there is too small a market, they don't bother.