I feel really dumb. I have been trying to use a PC mic with my Mac Pro so I can talk over iChat. I have a Webcam already, so I went to Staples and bought a PC mic. Just a mic with the standard plug. I plug it into the line-in jack in the Mac Pro (speakers are in the other jack).. nothing happens. So I assume the mac is busted. Get a different one. Same thing. Nothing. My Mac Pro will not pick up any sound. So I open the sound properties, and I see what I have attached. What the hell could I be missing here? Mic is plugged in to the line in, there's no on/off switch, and that's it right?