as so many average users requested i'd put this here:
if u wanna change to change the product ID in Windows XP, do it in both below:
go to Registry by Run > Type: Regedit
HKEY_LOCAL_MACHINE > Software > Microsoft > Windows > CurrentVersion > ProductId
HKEY_LOCAL_MACHINE > Software > Microsoft > WindowsNT > CurrentVersion > ProductId
you have to change the Product ID in both location, identically
