I'm building a MythTV box to replace my roommate's TiVo (he's moving out) and would like it to be in a nice case that would fit on a shelf with my other components. I've seen the Coolermaster 620 which would be perfect, but I don't believe it has a built in IR receiver. I also found this case (Strata) with built-in front IR, but I'm not sure I really like the look of it. What have people used for their cases, and what do you use for an IR receiver if your case does not have one built in?

well I'm using the coolermaster 620 with the ir receiver that came with my pvr250. It's not built in, but it's a fairly small cord that I run under the edge of the unit and hang off the edge of the rack.

These are the cases I'm considering:

http://www.quietpc.com/uk/cases.php#htpc

http://www.iuneed.com/products.html

I think they're just perfect for MythTV.

only Micro-ATX motherboard fits In those kinds of cases, right?
Which of these micro-atx motherboard is automatically supported by KnoppMyth ?

Not sure to which cases you refer iceheart78, but the Coolermaster cases fit MicroATX and the IUneed / Ahanix / Dign cases fit both Full sized ATX and Micro ATX motherboards.
I have bought the Dign 3B case. I could fit the IR receiver that came with the PVR-350 easily behind the smoke glass window in the case.

Here is one my friend is using. Fits standard sized mobo's. The thing to watch out for is the placement of the first PCI slot. Some mobo's have the CNR near the AGP slot, which push all the other slots over. This will make it impossible to use the 90 degree pci angle card to fit in the PVR card without cutting out the back brackets. A chaintech 7nif2 uATX mobo will work perfectly, for example.

The only other thing with this case is that it uses slim cd/dvd. It's roughly $80.00 for a DVD that will fit this case.

I use the Shuttle XPC Sn41G2B personally, but this one looks like a toaster, so it depends on your preference.

http://www.newegg.com/app/ViewProductDesc.asp?description=11-163-006&depa=0