Geforce GTX 560 vs 560 Ti

The gtx 560 ti is definitely the better card (but thats to be expected)
the difference is the ti has 384 cores and the regular has 336

I dont know how set you are on a nvidia but if your not i would recommend the radeon HD 6950. pretty much competes head on with the 560ti and exceeds it in some areas. also theres a 2gb version for around the same price as the 1gb ti. Just seems like a more bang for your buck deal

but to answer your question. If your willing to spend the extra money and you want a nvidia. Go with the GTX 560 Ti