iPod music transfer

Hi all, my dell laptop recently broke with the harddrive being wiped. With it working again and nothing on it i lost all my music off of itunes. Although it is all on my iPod 3G model. Do u know a way of transfering all my music on to the harddrive off of my ipod, if not with a blank itunes, when i plug im my ipod to itunes to load new music on without the previous music will it delete all music on my ipod thats not currently on itunes if that makes sense. please need help.

cheers

cheers mate your a lifesaver