Wouldn't you then need to add in either a switch or relay to turn the pump off when the computer isnt in use?
Using a switch would be the easiest, simply run the leads down to the switch from the power supply input, wire the switch up and run the leads to an electrical plug.
If using a relay (which is good because then the pump turns on when the computer does, so you dont forget the pump), you would need to wire the relay using the 12V line from the power supply to trigger the relay to turn on the 120V line to the pump.
I think there are some howto's on setting up a relay floating around the place, or someone who isnt quite as dodgy an electrical person as me can give you a schematic. I tend to just eye it up and work it out in my head, and wire as i go.
Ive got some plans tho for doing a relay system, using a small controller box inside the case to house the relay and wiring, then route a light and alarm out to the front of the case to show pump status and the alarm for if the relay doesnt switch. Also it means i dont need to cut up the power cable for the pump, so like was said i dont void my warranty.
*end long post*
