I'm currently using a macbook, running leopard OX S. Recently, I bought a headset with a mic attached so that I will be able to do video chat with my friends on skype or iChat. I don't want to use the inbuilt microphone because I want to minimize the background sound disturbance. But I am not able to get the line-in mic to work. It works fine on my PC and not my macbook. Is there such thing as compatibility..i mean between mac and headset with mic?