Pc to Pc calls - Voice chat and video chat

We are about to start a social networking site and would like to integrate Voice chat and video chat with our social networking site. We need a few customizations (similar to skype but the features should be embeded on our site) Requirements: We need our users to interact with their friends with features below Free Pc to Pc Voice Calls Free Pc to Pc Video Calls Instant Messaging Group Conversation File Sharing Screen Sharing Free Pc to Pc Conference Calls to view old conversation