cjrgreen: I run a Q9550 (minor OC to 3.33 GHz) and GTX 285, and it keeps frame rate consistently in the 40's at 1920x1080 and Ultra (less Ubersampling). Since none of nVidia's recent single GPU cards can keep up with the 285, the best you should expect is probably equal to that.
If you want a consistent 60 fps, you are probably going to need a 590 or an SLI setup. The CPU is usually not limiting in this game.
Hmm, that does seem unusually close to my performance. I don't know exactly how much faster my card is than yours but it should be somewhat faster at least. What drivers are you running or ran when you played the game? I've the 275.33, have been very stable for almost all my games so far since they arrived.
EDIT: Lovag@ About the HDD, I had it installed on a Intel 120GB which has fairly fast read speeds, its write are slower than other SSDs and the fastest mechanical HDDs.
I've should have added the reason I thought my CPU could be a limiting factor is that I read when the game was released it was suppose to make use of four corse but maybne it doesn't and/or when I reduce from max settings to mix of medium to even low settings I gain almost no FPS boost which mean either the game has horrible increase performance/eye candy ratio because the game initially is quite demanding (even on low settings) or I am heavily CPU limited. I figured that OC (I usually run my Q9550 at 3.4GHz on new games) and some more tweaking could help but not as much as I like so I thought I might as well wait since this game's graphics is a strong factor and I don't want to skimp on either performance and graphics since both mean quite a bit to me especially in a game like this I know I will like.