xbox live membership card question

i was wondering if a xbox 360 gold xbox live membership card worked for the old xbox because my 360 broke and now i have to wait to get it fixed so i thought i would just start an account on my old xbox until my 360 is finished. also will i be able to download the new account to my 360 when it is fixed.

You can just recover your current account.darkplayer

can i recover it back to my 360 when its fixed without messing it up, because i remember reading somewhere that if you download it to two sytems, or hardrives it can mess it up.