What should I do to increase the quality of online games on my computer?

To be more specific, I need a video card greater than or equal to 128MB memory and a CPU speed greater than or equal to 2400 MHz. I know someone who has the same computer as I do, and yet his online games have better quality. I don’t think he knows specifically what he did to make that possible. Can someone tell me how to fulfill these requirements for best play?