I dont think that it will make much difference...coz at very high setting the game is increasing the texture load and shader loads and all, which are directly associated with ur graphic card
Looks like FarCry 2 release is again delayed(Wikipedia)...
Here is the official system requirement
Minimum:
Windows XP with Service Pack 2 or Windows Vista
Pentium 4 3.2 GHz, Pentium D 2.66 Ghz, AMD Athlon 64 3500+ or better
1 GB RAM
12 GB of free space
NVidia 6800 or ATI X1650 or better; must support Pixel Shader 3.0
Recommended:
Windows XP with Service Pack 2 or Windows Vista
Intel Core 2 Duo Family, AMD 64 X2 5200+, AMD Phenom or better
2 GB RAM
12 GB of free space
NVidia 8600 GTS or better, ATI X1900 or better