hey, i have had this problem for a little while but just recently ive needed to deal with it. i purchased a sony vaio PC about 3 years ago everythign worked fine and dandy till recently. finnaly the harddrive is giving out so im due to replace it i ordered a new harddrive and a new motherboard from newegg got them recently but heres where things get confusing. i have heard that OEM copies of windows like the one i have can only be installed once? so will i be able to put my new main board in and my new harddrive and reinstall windows? or will it not work? ive read on other forums that i wont be able to activate it because it will see the new main board and no longer work? can someone explain... i dont have the extra money to buy a retail copy of windows. i do have my OEM CD and a OEM windows key that came with my origial system. the key from the sticker on the back of the tower. anyway before i rant on ill let someone reply thanks guys!