I think the CPU is THE most important part of any system. And I'm a hard core gamer, it's all I do. But I'm also an overclocker and I love me some fast benchmarks.
Personally I'd go with the i5 as it'll help out EVERYTHING you do, including graphics. The 660 will only help graphics. Why not get the 650Ti Boost edition as it's only 150$ for the 1GB and it performs almost like a 660. You can get the best of both worlds by going this route. ANd I highly recommend you go this route.
Personally I wouldn't get an i3 because it only has 2 cores and Hyperthreading those two cores will never be as powerful as having 4 real cores.
So yeah, get the 660Ti Boost 1GB for 150$ and the i5 and call it a day.
THAT's your best answer.
Anyone here would prefer an i3 and a GTX660 over an i5 and a GTX 650Ti Boost? I didn't think so. I'd even prefer an i5 with a regular 650Ti over an i3 with a 660. And yes a 660 CAN max out Far Cry 3. I know because I can on my 660Ti and a regular 660 isnt' THAT much slower.