Well, I originally planned to wire it from "the box on the wall." This is fairly close to where I would put the board. With that premise, where would I attach the wire from the box to the Arduino? Would it just be a digital pin? Also how many volts can the Arduino withstand. The board is a Duemilanove.
Now with your other idea, using the actual button, how would I do that? The button just completes the circuit when pushed, so where would I attach the wires for the Arduino?
Sorry for all the questions and confusion, but I really appreciate the help.