You DO NOT need server software to host/serve games. But to have a good server you need lots of ram and a good connection. I play Black Hawk Down and Comanche 4. I host games on that but the most I can get into my server is 8 people becuase of my connection. I have old cables running through my neigborhood. But after you forward ports or use the DMZ, you should be able to host a game. But after a certain amout of logins to your server, you should consider restarting it. I know this becuase Comanche 4 uses alot of resources..
anyways good luck with your server,