Well I don't know the specs for that GFX card, but regardless I'll tell you what I do know after playing for a couple days. My system is running a Core2Quad 2.4ghz CPU, nVidia GeForce GT 430 for GFX, and 5gigs of DDR2 (although only 4.5gigs can be used because at 4gigs+ Win7 64-bit will allocate and lock a portion solely for the OS)
Now, my CPU and RAM are both above the requirements for the game. The GT430 is exactly the card listed for minimum requirements. So I was expecting from the start that I wouldn't get -crazy- performance, but shouldn't have had problems getting 30+ FPS with lowered settings. Alas, after testing all settings several times, I always have the same basic results. At 1280x1024 and max, I'd get 18 low and 27 high, with the norm being 23-25. And at 640x480 and minimum, I got the same damn thing. Not really any changes at all from max to min. I'm guessing it's a game-related issue, since all my hardware is good and my drivers and such are all up to date. So hopefully a patch or fix of some sort will come along eventually.
Still, I'm about 30% through the game now, still running at full resolution and mostly max settings, and so far I haven't experienced any big freezes or very significant lag of any kind. It's definitely playable, even if it's not perfect