After a long time of suffering the low voice quality, the nonstop echos, the frequently freezing video (on both Mac and PC, but more on Mac). Some time ago I tested Google's chat (via gmail). Its a real small piece of installation (not the 40MB "skype"-like small), it works google-fluently, you use it through your browser, yet two Mac users can use iChat via this service (its easy), the voice quality is great (even when the two computers are in the same room there is NO ECHO), the video works every-time, you hardly notice the resources it uses, it is a part of your gmail-google account, and it works on Mac and PC alike. Having said that, I need not say what is my choice ...