I'm using a Creative Muvo v100, 1G unit. I try never to install the crappy software that comes with MP3 players, and this one is no exception. It works just fine on my Win2k machine without extra software, and should be okay on a Mac, just plug it into the USB port. I put nearly eight hours of podcasts on it, and only half-fill the space. Music files are typically less compressed, however.
But if you want lots and lots and lots of room, that 16G model you're looking at will be more attractive.