I am biased, but I would suggest the Citrix product line is the best fit of function, reliability and price - with the new Seminar version of GoToMeeting, the product line will cover the entire market space from small meetings to large global events.

I know price is an issue, but you want something reliable when meeting with customers and partners - and your choice of software also sends a subtle message, which is a reason to avoid using cheap or 'freeware' solutions.