939 Based media center PC, advice needed

OK, having done my x2 upgrade, i am now left with a Athlon64 3500+ Socket 939 CPU, 2gb of DDR, a 250gb SATA drive and a TV Tuner card (Hauppage HVR). I can get a Shuttle case from a friend for nothing (yay!) and am thinking a "below the tv" special to stream divx from my main pc, play dvds, record tv etc.
What i need is a decent Micro ATX Socket 939 board with integrated GFX and Sound to put it all into now. Has anyone any recommendations?

Also thinking of XP Media Center Edition for the UI, or alternatively MythTV (but can I read from shared dirs on my main Vista PC with Myth???)

Thanks in advance for any help u guys can offer :)

Won't the shuttle have it's own mainboard?

If not then an Abit NF95 GeForce 6100 board would be a decent low cost choice with good onboard video and sound

no, the shuttle case already has a system inside it, which i will be ripping out as it is ancient :)

I have a horrible feeling the mobo may be proprietary in the shuttles...

well, if it is, then can u recommend a good non-proprietary budget case for an under the tv pc?

Yeah you would be able to squeeze an ITX board in a shuttle with some modification but probably not a uATX board

If you want a stylish under the tele case then I'd give the Antec NSK2400 a thumbsup. It has two front drive bays which would be ideal for an lcd type display jobby. The PSU isn't the most silent unit in the world but the fairly low power requirements of an HTPC should keep the fan speed down, especially if you under clock/volt that cpu so you can passively cool it.