[Eudaimon]

Motherboard: most important thing is to make sure it fits with the CPU you're buying.

Second is what kind of RAM it's compatible with. I'd suggest getting something that supports at least DDR 800; decent speed, easily available. Also make sure to take into account the number of slots it has for RAM. If it only has 2 slots, you probably want to get a large single chip of RAM rather than a double chip.

Also you've got to watch the size; you probably want a mini- or micro-ATX motherboard if you plan on getting one of those cubey cases. Just make sure your case mentions that it's compatible with your motherboard's form factor.

Now, expansion slots. The standard for for video cards these days is PCI-express. Faster is better, you should probably look for 16x for what you want. If you want to do one of those dual video cards things, you'll need two slots. It's always good to have a few PCI slots, as well, because you can get just about any kind of expansion you'd want with those.

I can't say I've looked much into sound cards. Suffice it to say that if you plan on always using headphones, you can probably get away with using the sound hardware built into the motherboard.

You might want to take note of the ports built into the motherboard, too, such as USB or ethernet. You can always add more with a PCI card, but if you don't have very many PCI slots it can get to be a problem.

Make sure you know what kind of drive attachments your motherboard can handle. You don't want to be buying SATA drives if your board only has EIDE ports.

So yeah, that's mostly what you want to look for in a motherboard.

[Eudaimon]

I'm currently running on a "small" computer I built this summer. Here's my case. I originally had some reservations because some reviews said it was a bit of a puzzle to fit everything in, but it really wasn't. I've only had a couple problems with it, the first being that my optical drive hates running on its side so I have to turn it horizontal for that, and the second is that there's no way for a full sized PCI card to fit in there normally. There are ways around this, but the main problem is that it's probably going to be pretty hard to find a video card that'll fit when I finally get around to it (I'm running on the built-in GeForce 6100 on my motherboard).

I can't say I've done a whole lot of research into cases, but really, just look around and find what you think looks good.

[Eudaimon]