I have got an arduino, but I'm not sure it would add anything in this case. I'm just wiring 3 switches up to input pins on a parallel port. All the computing is done er... in the computer:)
The problem was my over confidence with electronics, but the sensors i2i pointed me to are much easier to use.

The arduino is great. I followed a guide on the web to make an RFID door lock. It still amazes me how simple it was when I use it.:)