Interenet Voicechat programs

Proto, Jebus and I are planning to do something online but it requires the three of us to be online and chat with Microphones on our systems. Is there anything that we can use to do that which allows decently clear transmissions? I know Y!M does that and I dunno if AIM chatrooms can do that so are there any other options?

http://rogerwilco.gamespy.com/
It's supposed to be for games, but I guess you could use it for whatever you want. I don't know anything much about it though, so you'd have to figure it out yourself.