CrossRoads:
You're not using it correctly.
N-channel parts like to sink current.
Use a 150 ohm resistor between arduino pin and the gate.
Thanks for the reply. I think I might have fried my uno while testing this. It was getting very hot after sending 12v straight from the Vin to the gate of that transistor. Is it possible something was overloaded with current because I didn't use a resistor between the power source and the gate? Right now the on LED and L LED illuminate when I plug it in but I can't upload and the reset button doesn't affect it at all. I guess this is a lesson in how not to use the Vin. It didnt occur to me the kind of current I was driving to the gate, I guess I thought it had internal resistance? Does this add up or does it sound like another issue?
Thanks again for your help!