AMD FX-4100 Vs Phenom ii X4 955 | Compare Processors
Check the results , AMD FX 4100 is much better.
Anyway i recomend u get i5 or i7 by intel.
i5
AMD FX-4100 Vs Core i5-2400 | Compare Processors
Check Benchmarks.
i7.
AMD FX-4100 Vs Core i7-2600K | Compare Processors
Anyway u will be able to play BF3 , in Medium settings (60FPS) [i think...)
With i5 or i7 , all on Ultra with 50 -70 FPS.