I personally would go with the i5 and a 7750 (for now.)
The reasoning behind this is because the i5 is going to be a viable chip for much, MUCH longer than the i3 is, due to being a capable quad core. That means that you can save up and upgrade your graphics card, say, when the 8000 series comes out.
It's a lot easier to do that then to upgrade both your graphics card AND your processor, because an i3 wouldn't do anything but bottleneck way nicer cards anyways.