The Minimum requirement is -
AMD Radeon HD 4770
Nvidia GeForce 8800GT
Which is very modest, the Reccomended is - Radeon HD 6870, which implies if coupled with reccomended CPU, you should be able to max out the game.
So @ Black_Zion, when you say - "Your graphics card is to weak", that is very untrue, he is well above requirement to run this game, and should be able to maintain constant 60fps with med - high settings.
Its source engine and is very scalable.
But to OP your specs should handle it quite ok, just keep the texture quality to high / med , same for shadows. Dont go to crazy on AA.