In general, I'd recommend fine-tuning your settings rather than using presets. In pretty much every game, there's always one or two settings that really tank the framerate, while some other settings may be set to Ultra even on relatively low-end hardware with little performance impact. Its always worth putting in the effort to find what works best.
With a 280X I bet you could get most of the way to max settings. Antialiasing and ambient occlusion are often the first things I look at, since they are really expensive effects and less noticeable [to me] than textures or shadows, or whatever.