if i reinstall XP Pro to change my product key will i lose all my files and stuff. i have my important files backed up but don't want to backup replaceable stuff if i don't have to. and i have another question if i used the "%systemroot%\system32\oobe\msoobe.exe /a" command and changed my product i get that key in the "right click my computer in the general tab" place not the series of numbers that are given for the blacklisted keys. how will i know if my key is blacklisted???

just use xp cdkey changer, you don't have to reinstall.