Online Dedicated Server Help

I'd like to set up a dedicated online server for Enemy Territory using my mom's old computer. I have installed the game and I tried to run the server, but it never happened. Im almost 90% sure it is a network problem. I tried dmz'ing that comp, no luck. What do I have to do now? Will I still be able to play the game using another computer on the network if the server is running? I am going to do some fishing and see if I can find out what port it uses and free it up, however I haven't had very good results with freeing up ports in the past, so you're advice would be appreciated.

Mike