I'll thirdeding, or whatever, the Creative comments, I have had two now with the only reason for buying the second one was that I ran out of space on the first.

I have the 30Gb Vision M and only use it for music, the battery life is good with one charge doing me a weeks worth of trips to work at 75mins each way, it's easy to use and the software for managing your music is straight forward.

I don't know about buying mp3 tracks as I get all of mine from err other places, Russia to be precise, mind you I haven't downloaded any in months so no idea if the site is even still active.