Never underestimate the power of miniaturization. This sucker can rock a Core2 Duo E6700 and 2 gigs of decent RAM, with room for four USB slots, two SATA ports, and audio and ethernet onboard. They call it barebone, they call it mini, but that’s probably a more dangerous system than some of our readers have.
It should be mighty cheap, too — boxes start at $99, or the price you pay for the black paint on your MacBook. If you get a Drobo (also boxy) you can sit them next to each other and they’ll look like siblings. I’d invest in a bigger PSU, though. The default 100W sounds a little weak.