It’s usually better to get better components than you need for when you upgrade your gear.
For example, you may think a crap video card will get you by when using standard NTSC (which stands for Never Twice the Same Color), but what about when you upgrade? Will your new HDTV have DVI, HDMI or component in and will you have to use an adapter? A cheap video card may have improper timings to support HDTV thru DVI. Both ATI and nVidia cards do HDTV over DVI ok (although some of the 5×00 series can be weird).
You may think that an onboard SPDIF connector is more than enough if you have an amplifier, but they can be very flaky. I have used several motherboards where the audio was unusable (would get crackling on hard drive access, or digital noise), and had to install a seperate sound card.
For a Media Center box, the motherboard doesn’t matter so much as the quality components you put in. Use a good seperate sound card, decent video card (nVidia 5200 or better), and a supported DVR card (the Hauppauge line works very well with Media Center). Figure out how much storage space you need and throw in a high-capacity drive.
If you are going to use an LCD for the front of your case, look for a motherboard with internal COM1 leads. That way you can attach your LCD to the motherboard directly without having to snake a COM cable to the back of your case.
Same thing with IR. If you are using Media Center, you may have to use MS’s USB-based IR receiver. You can use a USB plug to pin-head adapter (I’ve seen these around the interenet somewhere), and then connect the IR receiver internally. Just make sure your case has a plexi window that you can mount the receiver behind.
Some of the barebones kits are made for media center (I think Shuttle just made one with a cablecard slot for Media Center). Those may be perfect, as they are already tested for Media Center and have extra multimedia features (radio, CD and DVD player support to a custom display).
