Problem with integrate microphone

hi, i just convinced a friend to switch to a mac, he bought himself a new pwerbook 12 inch combo... and while we were experimenting with ichat audio chat, we found that his microphone was not working, i tried almost everything(Speech PPane, iChat pref) and couldnt find a solution... it just doesnt seem to work, the levels on the calibration pane in the speech preferences were moving but not because of the sound... does anyone know what can i do, is it off, or a hardware problem??