...and run the game between 30-40fps.
You say that as if it's a good thing.
What sorta systems are you guys running with such horrible performance?
I already listed my specs, which are actually higher than yours. The problem is that 30fps isn't very good, particularly when you're getting noticeable dips - it's not consistent. It feels really sluggish. You get used to it after a while until you leave the game for a bit and then it hits you when you go back to it. I haven't got around to completing it in large part because of the performance, despite the game being fun. It makes me worry about Doom 4 when they're aiming for 30fps - it just doesn't feel right in the games I've played.
I guess it's subjective but other games look and run better. GRID does driving better, looks stunning and has brilliant performance; Far Cry 2 does open worlds and, again, runs and looks great; Assassin's Creed does large open worlds and... etc, etc. All I know is that I have found performance in GTAIV to be seriously lacking and the graphics do not justify it.
"The price of freedom is eternal vigilance."