retail allows you to transfer the key if you ever upgrade or change a part. OEM is usually tied to the mobo that it is installed on and the code can be used once. so once you swap out the mobo, then you will probably have to buy another licence
ok thanks for the response and sorry it took me a while to make you BA ive been busy XD .
and i went ahead and took your advice and ordered my oem win 7 home prem from amazon last friday .