Chat Application Over a Network

I am creating a network theater full of cool things that people could do over a network connection, anyway, I want to know if I can send a line of text over a network to the other sides listbox without a server application. I need to do this because one of my tools is a network chat, and I do not want to have to give them a server client to run as well.

Anyone know how this can be done?

PS: In Visual Basic 6

you can use UDP where it doesnt need a connection to send data, but the side with the listbox has to be listening for the incoming data