I would check out kayako. They have a nice chat feature now and are always working on killer integration. You may choose to use it for support and chat and then just integrate it with a billing system like modernbill or clientexec.
I personally love phplive since I can host it myself and can get to the chat console from any OS.
I personally love phplive since I can host it myself and can get to the chat console from any OS.
