A few weeks back I finally decided to do something with an old computer that was just sitting around, so I put Ubuntu on it and made myself a fileserver. Next step was making all the stuff on the file server visible to the 360 so I could play music and video directly on it directly from the file server. uShare seems to be the answer for that.
There are several websites explaining how to do it, but I found this one to be the simplest. Just a few steps and you’re ready to go.