About product keys for windows xp...?

A Windows OS KEY can only be used on one computer. You can use the KEY 3 times on the same computer before you have to call Microsoft & turn in your old KEY & get a new one. If you try to use a KEY on more that one computer, it will invalidate the KEY & then Microsoft will consider the KEY invalid on both computers... Then you will have to buy 2 copies of Windows XP 1 for your computer, & 1 for your friends computer because Microsoft will kill that KEY #....

Unless you own a volume licensed key a product key can only be used on 1 computer and that's it. You can re-install windows XP as many times as you want on that 1 computer and the product key will work just fine. However if you try to use an already activate product key on another it will accept the key (when you install XP and it asks for a key) however when you have to activate windows it will not active it and after 30-60 days (depends on the version of windows) XP will stop working and you will have to enter a new valid product key or re-install XP to get it working again. So basically you can use the CD to install XP on your computer but you can not use the product key that came with it because it was already activated.

you need to get another windows XP

you can validate it even if it's in use on another active computer. i use only one product key for all my PCs. windows recognize them as genuine