I have had XP on this laptop since it first came out. It has been great and I have never had to reinstall it, like with windows 98, every month. Anyway, I have so much garbage that I have installed and forgotten about, it takes several minutes for it to boot up, and is showing its age (It is a PIII 800 MHz W/ 512). I want to wipe everything out and reinstall XP fresh. However there is one problem- my XP disc and it's case were both lost in the move. I DO own the disc, but as far as trying to find the serial for it, or even the disc, that isn't going to happen! Could I use my mum's XP disc, since my XP has already been "Authorized"? Will it still ask for the serial, or whathaveyou? I really don't want to spend $90 again for the upgrade.