Look on the bottom of the computer for the key.

sabrewolf,

The reinstall CD can be any CD but you will have to change the Product ID of the CD used to the one assigned to the copy of XP that came with your system (shown on the sticker) prior to activating the installation. See this. Of course, when you are prompted to enter the product ID during installation you must use the one valid for the CD you are using.

oh my... that should have been obvious, sorry :(

does the reinstall CD actually have to be another OEM CD or can it be a regular XP version?