Oh and another question:
If I have an iSight and my connected partner has a webcam on a PC can we chat?
What program does he use?
Summary of questions:
1) Instead of the iSight, what other webcam can I use on the mac?
2) What programs are out there so I can chat with an iSight, other than iChat AV?
3a) Can another person see me using an iSight, but he's on a Microsoft OS?
b) If so, what program would he use?