Self determing the server

Hi there, the program i am currently trying to write will have one server and many clients over an internal network. The problem is i need to know how to let the clients know the servers IP address altomaticly. And apart from pinging every ip address to see which response i don't know how to aaquire it.

Is there a more efficent method of getting the client programs to find the server when they turn on, or a way to make the server boardcast to every channel at once?

Tell the clients when you start them, either as a command-line parameter or as part of a configuration file.

Tell them what?

What the IP address of the server is.

Err, but i won't know what the IP of the server is though. I'm writing the program to sell as a package of a server and lots of clients. So the people buying it will be running the server on there computers, and i doubt they'll be computer literate.