David, we must think alike. I have wanted to do something similar for a while. In fact, two years ago I did some simple testing with a barrel in my basement, a small pump, a car radiator and fan. You can check it out here:
http://ecorenovator.org/forum/geothe...html#post14998
The results weren't an amazing amount of cooling, but it did work. Scaled up I don't see any reason why it wouldn't work quite well. Check out my thread and let me know what you think. The setup is not exactly the same, but similar.