Im running the windows 7 release candidate right now. do you think i can use the upgrade edition of windows 7 or do i have to buy a full version because i dont have a os i can use other than the rc version which will be starting to have bi hourly shutdowns in march. and i had this emachines, but i swapped out the motherboard and mostly all the parts, will the cd key on the case of xp be usable so i can install xp so i can buy a upgrade edition of windows 7? thanks