How to roll your own Mac for under 240$

I'm been looking for a way to play digital media (music, media) in the living room. It should be inexpensive and easy for the family (wife) to use. I would like for it to serve upiTunes music library and dvd library, play internet video (cbs, hulu, joost) AND record over the air TV. I am currently using boxee on a hacked AppleTV. It works OK for serving up movies. Not so good at music, although the built in frontrow software does a good job for music. It can't do PVR at all. I would rather use a mac mini but they are too expensive and I would also have to get a PVR card and would have to switch between boxee and PVR software. I might have to try this hardware seems pretty inexpensive maybe I could install mythbuntu and have boxee scan the mythbuntu folder tag it, and serve it up all in the boxee interface. Then could use as a media player and PVR.....hmmm??