Check out this chart from Cnet. As a whole it lists the most common MP3 players, and which music services it is compatible with. Then, if you click the picture of either an MP3 player of a music service, you'll get a full Cnet review, as well as the comments from other users.
Hope this helps,
I know there is itunes, but what are some of the other ones. Can someone tell me which ones are the best? I might be getting either the ipod mini or the creative zen micro and I need help deciding? Also I have a relatively slow computer I don't know if that matters much when downloading music.