Originally Posted by
terrac
this might not work if it's a different copy of XP. HOME - PRO or even sometimes a different brand install of the same version.

Worth a try though.
My guess is he's lost the original install CD and just put a dodgy copy on that wouldnt accept the keyfile on the dell sticker or probably didnt even bother with the key on the dell sticker. Knowing dell they'll charge you for a copy of the install cd.
Best bet would be to get a copy of a dell XP cd from somewhere dodgy or buy one from ebay and use the licence you have on the dell sticker. It should tell you on the sticker wether it's for home or pro.
Yea forgot that bit your right

, The Key needs to match your version eg home/ pro . Cant say i ever hit a problem with different brands though, and ive done to many install to remember, but you could be right.