The required things for source mods are the same of all the other source games, you need srcds (Search it in google) folllowing the instructions to install it, then download GoldenEye: Source 4.2.1 server and install it in the srcds folder (Intructions, thats 4.1 but still works:
http://wiki.geshl2.com/index.php/GE:S_v4.1_Server_Install ).
You have to open some ports too:
UDP 27000 to 27015 inclusive (Game client traffic)
TCP 27015 (SRCDS Rcon port)
Restart the router and then launch the server and wait people to join, test it with friends to see if it works, you can launch a listen server (In the menu) too but when you leave the game the server closes.
The ram doesn't really matter I think, and the HDD space needed depends in the game, 2-3gb maybe, the internet speed REALLY matter, in srcds page they have the required for "x" players.
Hope it helps.