FWIW, ABD
IMHO, < iSight is running a considerable risk of disappointment.
I communicate with a few people with other-than iSights.
arginal, at best. Expect "poor" and you won't ever be disappointed.
There's a market out there. Maybe ecamm with capture.
Even iSight/iChat is sensitive to bandwidth fluctuations.
USB cameras: Think Zune; Firewire: Think iPod
PS: I'll ask my loyal/friendly/insightful/good/true/reverent, international band of iSighters and we'll try ecamm's new PowerBoost app.