Nope, sorry. Can't help you.
I talked to a friend about this very problem. The best solution found was to use either experimental aMSN or to run an older (but supported) version of MSN Messenger to do A/V chats.
This person required chats for platforms as diverse as Macs, Windows, and Linux/GNU though. Your requirements are probably not as stringent.
There is a lot of good OSS software for (Linux only) A/V I believe. Never tried it myself since I lack the hardware.