PCGH got a hold of the benchmark tool in Far Cry 2 and shared for the results for you all to see:

In hight-end-class the Radeon HD 4870 with 512 MiByte is beating the new Geforce GTX 260 with 216 Shader ALUs in every test. It even offers enough performance to play at 1,920 x 1,200 with 4x FSAA and 4:1 AF. But the best performance is offered with an SLI setup: a second GTX 260 increases the performance by up to 81 percent. The Radeon HD 4870 X2 on the other hand isn't scaling very well though - we hope for a driver update. All our tests were run on DX10.

In the middle-class the Geforce 8800 GT and the 9800 GT offer the best price-performance-ratio. Even in DX10 and "Ultra High” Settings the Nvidia cards deliver payable 40 fps - as long as you don't activate Anti Aliasing. Geforce 9800 GTX+ and Radeon HD 4850 are a little faster indeed, but cost more, too.

All-clear: You don't need a high-end PC to run Far Cry 2 at playable framerates - even the "Ultra High” Settings are far from the brutal system requirements Crysis imposes. Even with a Core 2 Duo E6600 or an Athlon 64 X2 6000+ and a Geforce 9800 GT/8800 GT or a Radeon HD 4850 you can play the highest settings.