One for overall better performance, and one for gamers. I'll give you both and you can decide which is best for you. These setting assume that you have at least 16 megs of ram. If you have less than 16 megs of ram stop here. The goal here is to have as much free memory as possible for the game.
Most games tend to use as much memory as they can get.
And if they can't get enough, that means hitting the swap file. I always set the MinFileCache to 2048. The MaxFileCache is set to .25 times system memory. So if you have 32 megs of ram it would be 8 megs or 8192. The settings are in kilobytes.