Trying to be the clever one, I used my copy of Win XP Pro SP2 to do an "over-install" on a friend's computer. I've done it before, no problems. However, when I tried to used my friend's XP Pro key, Windows claimed it was invalid. My friend's copy of XP Pro is very original: not even SP1! Could that be the reason? Anyway, regardless of why XP is being a pig about it all, now I can't go use my friends original Win XP to get rid of the failed XP Pro SP2 install! The install gets as far as loading device drivers (34 mins left to go), then just sits there. I waited for 10 mins just to be sure. I know I can load his HDD up into my machine, copy off the my docs folder, then do a clean install, but it is all such a hassle farting about with hardware and software re-installs. I don't even know exactly what's on his HDD!! There MUST be a way to tell XP to sod off and use my friend's XP Pro key: it's definitely a legit copy, as is my XP Pro SP2. HELP!!!