Jitsi (64-bit)

Jitsi is an audio or video and chat communicator that supports protocols such as SIP, XMPP/Jabber, AIM/ICQ, Windows Live, and Yahoo. Jitsi can encrypt your calls using the innovative ZRTP. Show you're desktop to anyone with a video-capable XMPP or SIP client. Allow other Jitsi users to interact with your applications regardless of your OS. It features secure video calls, conferencing, chat, desktop sharing, file transfer, support for your favorite OS, and IM network.