A midrange CPU isn't gonna work either. While Tomshardware shows that average FPS is pretty close between various CPUs with the 8800GT (+/- 3 fps) the minimum framerate on a Athlon 4000+ is about half that of the top end Quad Cores.
This is what they mean by "first we are CPU-bound" (i.e., minimum fps), "second we are GPU bound" (i.e., a top end graphics card will up your average maybe to the mid 20s).
This is just not a playable game in this generation. I tried the Crysis demo and while it was pretty smooth in some areas, when the combat started (I guess all the physics calculations) the gameplay reduced to a slideshow, on my 4400+ with 8800GT @ 660/1900/1650.
Crysis I guess is a repeat of Far Cry. It's not the only one though, both Oblivion and Morrowind brought top end systems to their knees and even a generation later it wasn't exactly playable either at the highest settings...it took two full generations of GPUs before either game could be considered "playable."
But one thing that all four games have in common--they don't look good enough considering their system specs. Crysis has a lot of "cute effects" but if you remove that from the equation it looks pretty middling, the textures aren't that impressive nor the foilage, and the NK soldiers are all clones of each other.