Multimedia :: Multimedia System
DSL might be what you want. Be sure to check out dyne:bolic though. It's a media focused liveCD with emphasis on publishing content. It's worth a look.
dynebolic is focussed on audio/video production.
For media centre/home theatre setups you might be interested in -
MythTV, a bundled suite of applications. http://www.mythtv.org/
LinVDR, a small distribution. http://linvdr.org/projects/linvdr/index.en.php
epiOS, a larger distribution, Epia-friendly. http://www.epios.net/
original here.