Moovida is a media center with a smooth and slick interface, and I really liked it when I reviewed it a couple weeks ago. Moovida now has a plugin for Jamendo, the music 2.0 platform with all of their music under the Creative Commons umbrella of licenses.
The interface is strictly a streaming service for Jamendo. To download music, you will have to go to the Jamendo website.
Jamendo is a great place to look for new music. As I said before, all of the music on Jamendo is available under a Creative Commons license and is freely downloadable. If you have never heard of it before, go check it out too!