Hi we already developed this types of project, and let me tell that we develop it in VC++. where one control server is there and clients or users are connected to the server dynamically and the information of all the clients are listed in the view area of avery clients. They can pass Audio, video and files in between them. If You want tyo develop this project in .Net and java then donot worry about it. It will be more easier.
For any kind of demo please fell free to mail me or call me.