XBMC

XBMC is a media center application for Linux, Mac OS X, Windows and the XBox.

It makes an excelent hub for all your media,and can even act as a server for other XBMC or other compatable media players (UPnP and DLNA).

Supported Operating Systems

 * Linux: Supports the x86 architecture (Ubuntu is recomended)
 * Mac: Suppots OS X 10.4 and 10.5 on x86 and PPC as well as Apple TV
 * Windows: Suppots XP/Vista wiht x86 architecture
 * Xbox: Supports any modded retail Xbox (see the | wikepedia article on Xbox)