The XboxMediaCenter Project:

XboxMediaCenter is a free open source (GPL) multimedia player for the Xbox™ from Microsoft. (XboxMediaCenter is also known as "Xbox Media Center" or simply "XBMC").

Currently the XboxMediaCenter can be used to play and view supported video/audio/picture formats such as MPEG-1/2, DivX, XVID, MP3, JPG and more direct from a CD/DVD in the Xbox™ DVD-ROM or of the Xbox™ hard disk drive, it can also play files from a PC over a LAN / network via an XNS (XStream Server) software or from a windows (SMB) share. It has playlist and slideshow. These features enable the Xbox™ running XboxMediaCenter to fully function as a multi-media jukebox.

Note! XBMC is a hobby project that is only developed by volunteers in their spare-time for free.
(Remember XboxMediaCenter does require a Xbox mod-chip installed in the Xbox™ to work).

Check out all the screenshots on their website. (link featured below)