Heya, the department I'm helping out at recently bought 3 Mac Pro machines with 2.66Ghz, 4GB RAM and the nVidia Quadro boards. Now the computer room is hot as it is and the additions didn't help ...

According to the data sheets, various vendor power calculators and reasonable guesses, the power consumption of all equipment in the room comes to about 2200W, and the heat dissipation is 5500 BTU/hr.