If you're having a problem getting iChat to work correctly, here are some things to check (in order of likelihood of fixing some connection problems):
- In Apple/System Preferences/Sharing make sure Internet Sharing is OFF
- In Apple/System Preferences/Quicktime/Streaming/Streaming set the Quicktime streaming speed to 1.5mbps
- In iChat's Preferences click on Video and change Bandwidth limit to 500
- Check this Apple support document (http://support.apple.com/kb/HT1507?viewlocale=en_US)
- Enable the following ports in your router (check router documentation for How To):
- UDP 5060, 5190, 5297, 5298, 5353, 5678, 16384-16403
- TCP 5190, 5220, 5222, 5223, 5298