Well first up, are you talking setting up a Dedicated server, or just hosting one on the session you are playing on?
Best way would be a dedicated server, machine doesn't have to be powerful in the slightest, hell i've run a dedi COD2 server on a P3 700 with 256MB of RAM and onboard intel video, seeing as its doing no rendering, its not an issue.
That way, you can use programs like rcon4cod2 to change all your settings, map, weapons that are on or off, map rotation, time limits, game type, etc etc. If you are going to be playing S&D primarily, then I'd also suggest installing PAM onto your installation, it makes the whole game that much smoother to host.
If you are just going to host a game on your own machine, in the same session you are playing from, just use the in game "start new server", Choose a gametype, and launch a map. To administer it bring down the console, for example to change map, type in "/map mp_mapname" (where mapname is the name of the map you want e.g. mp_toujane). The server is connectable through the console on the other PC's by typing "/connect 192.168.0.1; password password" (where 192.168.0.1 is your PC's LAN IP address, and password is the password you chose IF you chose one).
There are a huge number of variables you can set on a server either through RCON or locally on a local server.
