I'm building a new machine and am on my last part, the graphics card. I know that I want a Nvidia from eVGA. I've been trying to do some research but I'm just not that equipped (knowledge wise) to make a solid purchase.
I'd say wait if you can. The 660ti is just around the corner and should have significantly better performance at a similar price point. It will at least shake the pricing structure up and you may wind up being able to get the 7850 (which is a better card) for ~$200.
If you can't wait, the 560ti for $200 is a decent buy. It will play everything as long as you don't expect to be able to crank up anti-aliasing on the most demanding title.