Clientside method: Java applet using sockets. Simple. (the irc protocol isn't too bad to do simple stuff) - look at iirc jIRC for code examples
Serverside method: Oooh nasteh, any server side scripting language that allows you to connect to sockets... PHP will, I expect ASP can. You keep the page refeshing often which is nasty, but you could look at how CGI-IRC does it.
(This is all on top of the IRC protocol btw).
Thanks, well I have to get this up and running tonight and haven't done PHP or CGI yet. I know this is not the ideal solution but its only going to be online for a week.
Thanks for all your input.
Are these Java applets ready made? Do they have loads of banner adds with them and stuff? If not I would consider using an applet, it may solve a lot of my problems.