Generally the selection of CPU does not determine which is a better GPU or vice versa. Intel CPUs work well with both AMD and Nvidia, as AMD CPUs work well with both AMD and Nvidia GPUs.
Of the two systems liste by saint19 the Intel is far better for almost all uses. However, as you are not a hardcore gamer, you can probably get by with a lesser Intel processor and still have a very good system. The Intel i3 2100 series might be a better budget choice for your rig. But if you want the i5 2500K, all I can say is that it is aphenomenal chip.