Just wanted to clarify that my intent was to have the arduino off, and when motion is sensed by the PIR (which is always on) then starts the arduino (boots it up) then when motion is gone the PIR signal drops back down to 0, and the transistor stops the flow of electricity to the arduino.
I have relays, but the PIR wont be able to turn them on. Part of this for me is to learn more about transistors, I thought a transistor would be more appropriate in this case.
This is different than most implementations I have seen, most of them have a loop, an interrupt, or a watch dog. In this case if there is no motion, there should be no power to the arduino.