As mentioned in another Thread "FILE RECOVERY", I'm trying to reinstall XP on my friends PC. This PC was built by a friend of his some years ago, and he has since died. My friend never got any Install discs from his friend. I've got XP installed using my Install disc, but now it's looking for the 25 character product key for XP. I tried using mine but it said it was invalid. Any suggestions as to how I can input a product key. I'm getting a message that system will run for 30 days, but I've got to activate XP somehow.