This mobo seems to work perfectly. It's an Nvidia nforce2 based board with integrated Nvidia gf4mx vga. No additional things to but. It's also got a built-in tv-out connector. This board is basically the equiv. of the Chaintech 7nif2 mobo as far as features and complete integration.

Basically, you need to add ram, cpu, disk(s), pvr card and you can then use your myth box with your tv set using the tv-out without too much hassle.

http://www.msicomputer.com/product/p_spec.asp?model=K7N2GM-L&class=mb

What case did you use ?
What case would you recommend ?
Where can I find info on your install ?
I think I would like to use the motherboard you have since it has a built in tv out connector.

Lots of folks around here use motherboards with nforce2 IGP chipsets like this one, far too many to provide links to them all. However I can give you a recipe for how to look this up for yourself and get better suggestions:

1) Use the NewEgg motherboard page to find maker's model numbers:

http://www.newegg.com/app/manufact.asp?catalog=22&DEPA=1

2) Use those model numbers to search in the forums here:

http://mysettopbox.tv/phpBB2/search.php

3) Look for cases paired with those boards.

4) Provide more information about what type of case you're looking for and what pressures will influence your decision (price, size, looks, expandability, ...) The Athenatech cases have been mentioned more than once but they look a bit cramped to me, the Antech Aria is another possibility but may be rather tight around the mobo, the APEX Super Case gets great press at NewEgg, ...

I used an NForce2 IGP based SFF box as my starting point and my main regret is the severely limited expansion options.