Thanks all,
I don't think frost will be an issue in my situation. I only want to bring the temp to around 40 to 50 F, not -40 to -50 F.
As to the gel stuff; I don't want to go that far. My wife already thinks I'm crazy when she saw the size of the heatsink I just put in (Volcano 7+), I can only image what she would think if I started pouring that gel stuff in my PC!
The big fan idea is not really ideal. I had to do that once or twice this summer and I didn't like it. Plus it's not a neat mod.
Condenstation
in my case shouldn't be a problem either. Remember, condensation needs two things to happen: moisture and a difference in temperature. An AC unit dehumidifies by nature, and since the air will be a closed-loop, there shouldn't be much moisture at all. I do predict I'll have some moisture beads on the outside of the case itself since the whole interior will be cool compared to the outside temperature/humidty, but thats no big deal, my case is aluminum: won't rust.
A window AC unit, even a small 5500btu one, is really too big. I'd basically have to have another PC case just to house the thing. Plus a window AC is meant to cool around 1,500 cubic feet, my case only has 1.5 cubic feet. That would be like putting a 130,000 horsepower motor in my Ford Countour.
A car AC uses the motor to run the compressor, not to mention that's really too big too. That's why I thought the assembly from a mini fridge would work better. The cooling space is about the same, and since it's meant to cool to about 30 degrees, it wouldn't have to work too hard at all to keep the PC to 40-50 degrees.
I'm still looking around to see if I can find an old mini-fridge to work with. I'll keep everyone posted.