[andrewas]

OpenGL is a graphics API. Basicaly, its a language that the application can speak and that can be translated into something the card can understand. DirectX is another API. Which one you use depends on the game in question and which ones your card likes - experiment with it if you have the option.

I always go for performance. Beautiful graphics never won anyone anything. If you can set for quality and still get good performance, go for it. But don't compromise performance for quality.