Well I'm taking my first foray into the MythTV world today. I have an oldish (500 MHz) laptop with gentoo installed that I'm going to try it out on. For the time being, I'm only going to use the mythmusic and mythweather modules (and also a picture browser, if they have one), as I really have no need for PVR functionality. The laptop, a Dell CPx has an s-video out port, so I'm hoping I'll be able to get myth to display on that so I can display it on my TV. If it all works out, I'll purchase an IR reciever/remote and get lirc set up so I can control the tunez from the couch.
Wish me luck!