Transferring with a flash drive?

Didn't know where to put this thread but just checking real fast this question..

If you use a flash drive to transfer your stuff from one hard drive to a new one on the X-box 360 console, will the map packs from Call of Duty and other games still be able to be played or will it only work on the original hard drive?

 

Map packs will be attached to the gamertag, so you just redownload them from xboxlive(pretty sure the game will update by it's self? not 100% certain)