How much ram should you put in your server for a game like BF2 or CSS with a Quadcore.
Ram is fairly cheap, what processor is it running and how many people will it be supporting? I would suggest 8GB of low latency ECC RAM assuming its a real server, or just 8GB of low latency ram if its a PC box that got converted to a server role.
If it is on a x58 board, go with 12Gigs. I don't think that you will need more than that.