Okay, my younger brother won a semi old computer form his school.
Its loaded with Windows 2000 Professional, the computer once had XP Pro on it (has a sticker with product key on it).
If I "obtain" an XP installer, would the key work? And if it does not work, will the computer roll back to 2000? I don't know much about computers (heh) and just want to make sure before I attempt.