Time Machine Question

Hey guys, next month i'm hoping to buy the new macbook pro, hopefully with processor upgrades but i'll have to wait and see, i'm going to buy a new external hdd in the next couple of weeks to start getting things off my old desktop machine, my question is, if i wanted to use time machine do i have to use a seperate drive, or does it just create a folder on a drive and you can copy music, videos etc to keep externally?

Time Machine will make the entire drive its own, as it will keep making backups until the disk is full. The solution is to partition the drive, and only allow time machine to use one of the partitions.