I want to transfer my iTunes library to an external hard drive to back it up but to free up space on my computers hard drive as well. Do all the movies, shows, & music already have to be saved to the computers hard drive to copy it to the external drive or is there another way? Not all of my purchases have been downloaded to my computer from iTunes because I don't have the space. And downloading them a few at a time is becoming a pain & I really don't have time to do it.