Zune Media Player Software
Zune Media Player has all the features you'd expect in a full-featured media player, including multiple ways to manage your library, as well as creating playlists and ripping and burning music. Most interesting, though, are some of its more advanced features. For example, you can participate in what's called the Zune Social Community, which is made up of users of the Zune and Zune Media Player. You'll be able to recommend music and videos to others, and get their recommendations as well.
The Zune Media Player software is free. If you like, though you can pay $15 per month to download and stream unlimited songs from the Zune Marketplace, an associated online music and video store.