I just found this today:
http://www.tv-server.co.uk/content/tv-server/mp100n.htm
FAST Media Player.
Similar to a number of other devices of course. Network player for audio and video. If you already have your music on a computer that is always acting as a server there's no need to set up another server. I'm mostly interested in something like this for playing back movies instead of fiddling with Windows software through TV-Out. Even though I will already have the PC right by the TV, I'd still consider going through the interface of a network device if only to make the experience that much more consumer-electronics-like.
Bruno