Setting Up A Linux Media Box

So I've got an old computer that I've used to play with Linux on a bit, just so I don't break anything on my main box and I've been thinking about throwing Ubuntu and MythTV on there and turning into a nice little media box.

I would need to buy a TV tuner (one w/ a remote). Would I have an issue finding one that would work w/ Linux or would any one that says it works w/ XP work fine?

Any recommendations? I'm not looking for really high end, I want this to be a cheap little project, but I don't want something that's just going to crap out on me.

Mainly I want to be able to watch downloaded videos, network in all of my roommate's music, and maybe have some DVR type functionality. And I want to be able to use remote for the interface most of the time.