I seen a thread where a guy dug a big hole, and used an old propane cylnder filled with water, ran a pipe system through it, too and from the PC, burried it in the hole and used this as a heat exchanger. Ground temp is very constant most year round, and the large surface area made for efficient cooling.
My rig is near my from door, I have always thought of trying this, but i think my wife would think me nuts (probably on the meths) and leave!
I do thing the meths idea a little risky. Get a cheep fridge/freezer from argroos and make a chiller block.....