I can run on 25-50 frames a second on 1024, but when i bump it up to 1280 (my monitors standard) i cannot run it faster than 25 frames a second. But my video card it much older than yours.
Have you tried disabling the check boxes for "sun shadow" and "grass shadow". I don't remember their exact names, but they are similar to that and give my game an enormous framerate boost.
Edit: Sorry, i just turned the conversation around and turned it into a Stalker thread. Feel free to go back to the original discussion!