I'm considering getting an iPod Shuffle, but I have one important question. I'm not the type of person who has a lot of MP3s - usually, very few. I'll listen to a few songs for awhile, then move on to different ones. So my question is, once I put a few songs onto the Shuffle, can I replace/delete them, re-gain space, and put new ones on? Prob a dumb question... but I need to know.