Will windows vista UPDATE, replace my "unvalidated" copy of windows XP?

I have windows xp pro. when i try to update it or other windows programs, i'm told it's not a valid version. I figure i'll buy the Vista in a few weeks. BUT....will the update work or will i have to buy the full version?

Will windows vista UPDATE, replace my "unvalidated" copy of windows XP?microsoft office 2007

Yes it will.

Will windows vista UPDATE, replace my "unvalidated" copy of windows XP?windows media internet explorer

Buy full version .