Voice chat program suggestion

[Autolycus]

Does anyone know of a voice chat program for Windows, preferably free, that allows you to set the volume level of each individual user?

We're trying to setup a networked PnP D&D game, and I can't find such an option in either Teamspeak 3 or Ventrilo.

Edit: Also, we need it to allow users to choose between push-to-talk, voice activation, and "always on".

Edit 2: I made the OP assuming that individual volume control is the solution to my group's problem. But since I'm sleep deprived and just in case I missed a better solution, please let me state the problem.

We have a gaming room with a central speaker and mic where several people meet for gaming. A couple of us are remote. Using TS 3, the remote people have to crank the playback volume very high to hear everyone in the game room. Unfortunately, when one of the remote players talks, it deafens the other remote people.

Suggestions?