Sorry Ken - my wife returned it to Value Village. I still wouldn't mind an XBOX - but now am looking at the mediatomb / boxee / etc that people have mentioned. I still really like the TVersity (Windows only though) as it does on-the-fly transcoding based on the devices profile. From my surfing I don't think mediatomb and the other servers can do that "out of the box".
I've tried TVersity, and I really can't stand the way the 360 handles things. The interface is so basic and craptacular for playing back media on the 360, and requiring a media server is ridiculous. I wish they'd just support SMB.