Does anyone have experience and an opinion about which webinar software is best? I'd like to add a feature to my website whereby I give video seminars and allow users to type questions for me to answer live. I'd also the webinar to work as a chat seminar for my users who cannot view video. I want this to be integrated into my site (with no one's logo showing) versus having my clients link to another site.

What is the best low cost or open source software for this?

thanks for your help.