I would say get the i3 over the 4100, but if you can get the FX 6300 as it is better than both and should be around the same price as the i3 if not cheaper. Also, go for the 7850, it's much better.
The FX 6300 and 7850 would make you a nice little AMD rig that could handle BF3 on high at most resolutions no problem.