Listing all the computers connected to the network.

Hey,

I am creating a tool that gives me the ip of the local server pc wich ip changes often, I want the program to generate a list of all the computers connected to the network and then check each ip for the server. This brings me to the problem, how do I get a list of all the computers on the network?

If you are wondering why the server ip changes so often, this project is for school, we use removable hdd's to work and when we slide it in one of the computers and boot it will have another ip. I need my classmates to know the ip of my computer so that they can connect to my irc and ftp server.

Thanks in advance!

Jason