Sure !
Except... It better be a legit copy of XP that you have purchased on-line from Microshaft or you will be sitting there with a turkey after 30 days.
Oh, and Vista, unless this has been changed very recently has only one good thing going for it... You are allowed to install an earlier version of Windows without having to
first format your hard disk drive as was the case with XP.
That's the ONLY positive thing about Vista.
If you are seriously of the opinion that you can download a copy of XP that someone is sharing on the network AND actually expect it to work, you have some surprises coming down the pike, as they say ! LOL
It is also completely against the rules of this forum to discuss such things as actions that refer to copyright infringement - But, in this case, go for it !
It won't work out for you and it will be a great lesson, huh ?