Ok, this thread is really old, but I think I've found the answer!
I was just browsing around Target one day in the automotive section when I noticed a small refrigerator designed for a car. Its just big enough for a few cans of soda and a few sandwiches, but its only about 12" x 6" x 6", and most of that is the refrigerated interior. The box says it will lower the temp to about 45 degress F lower than ambient. Even if my house is 85, itll keep a pc at least 50-55 degrees given the size compared to the refrigerator interior. It runs on either 12 volts (4.6amps...a bit high for a PC supply though) or 110v AC and costs $50.
Next paycheck, I'll pick one up, rip out the AC core, seal up my PC and give it a whirl as a closed-loop system. I'll post back here with results as soon as I get results.