My system: C2D E7200 3.8ghz
560 GTX 1gb
In order to even semi-reliably hit 60fps I have to run 1280x1080 rendering resolution with no SMAA, SSAO or DOF blur, and with DOF set at 540; it's still hit and miss and I found the constant framerate jumps jarring. I settled for playing at 30fps with all the trimmings at 1080p (810 DOF), which is wonderful: it still feels more responsive than the PS3 version did, and it looks
fantastic. However, make sure you enable the key bindings to turn said trimmings on and off, as I found that I had to lose some stuff to make it through the forest, Blight Town, the (really really good) DLC areas, and a few other places, at 30fps.
Heading into NG+ now