Solved: Reinstalling XP

Of my two copies(licenses) for windows xp one is an upgrade version and one is a full version. If I need to reinstall on the computer that was using the upgrade version, do I have to go through installing 2000 and then upgrading, or is there a way I can use the other copy and the key from the upgrade version (or would I use the key from 2k?)?

 

Great, thanks. I'll have to remember that for the future about the upgrade CD. I had forgotten the order that things happen in and that it would see the current version first before reformatting the drive.
What I ended up doing was I just what I thought for sure I couldn't do. I used the full-version CD and when I tried putting in the key from the upgrade it didn't accept it, just as you said (but I swear someone had told me before that it would). So just for the heck of it, I input the key that goes with that cd (but is already in use on my other system) thinking it either wouldn't install or wouldn't activate, but it did, and it's even patched and passed the windows GA test. I had to buy the second copy last year because the upgrade copy wouldn't install on both computers, and now apparently it is letting me install the same (full-version) on both.... Go figure.