I completely disagree with the above statement. You will waste your money getting a cheaper video card at this point. Main reason, is if you get the 750 Ti, you can always upgrade your cpu/motherboard and keep the 750Ti. If you get a faster processor for an older motherboard and bought a cheap video card, you would of wasted $100 easily and will still have to upgrade everything.
As for video games, your video card (gpu) is the most important part of your system. Second will be your CPU. So it will be wiser to get a 750Ti rather than a 6670, 730, etc.. spend an extra $40 or so and get a much better card, i.e. the 750Ti. Then you can upgrade your cpu.
As for bottlenecks, in more often than none, many bottlenecks stem from having a slower video card. CPU's main purpose is for physics and isn't used nearly as much as displaying images, how fast textures show, draw distance, etc.. - all the things a video card is responsible for.
Trust me. Get AT LEAST a 750 Ti 2GB. You can always move it to your next computer build.