"XBMC is by far, one of the best media centers around.
Originally built for Xbox, the XBMC team has now ported the popular
software to the various platforms, including Linux, OSX and
Windows. It supports a wide range of protocols and audio/video
formats, making it a versatile media player that you want to have
in your system.
"With XBMC, not only can you enjoy your audio/videos/images that
are stored in your local drive, you can also stream the multimedia
content from the Web, via network share, SAMBA or even from uPnP