System performance equality - what GPU works in tandem

And now a little blurb to better explain and for those who like to read :

Hello,

I've read literally dozens upon dozens of threads here about different computer parts and finally found myself at a point in my build where I am unsure where to go next.

I'm building a middle-ish grade desktop pc and I find myself wondering what parts of my build will exploit the best aspects of each other.

The very basic question is : what GPU should I get?

So far I have core i3 2100, 8 GB ram, Z77 MSI motherboard, Kingston 128 GB SSD. And now I'm picking the graphics card. I will use the computer for everything but primarily for web browsing and new video games that I haven't been able to buy/play since All I've had is an old dusty crusty Sony pc from '04  

I have had my eyes and heart set on nvidia gtx 560 as it had a very high value per dollar rating. But the more I read stats the more I realize its quite a decent card and I think it may be better than or " out-perform " my system build to the point I won't be able to use what I buy and with a slower processor I might as well just get a gtx 650 instead. Especially considering the power draw the 560 needs.

And I am brand new to computers, can someone tell me how this card is powered? Does it take 2, 6 pin power plugs from the PSU?

Thanks!

Wouldnt be overly concerned about bottlenecking on this rig. Only in CPU intensive games (which most arent) will the card be held back by the processor.

At your price point, theres the GTX650Ti and HD7850 1GB (Not much point getting the older Fermi cards).
http://www.anandtech.com/bench/Product/549?vs=680
As you can see, the 650Ti gets outperformed by a large margin by the 7850. It also has stronger compute capabilities, which will help on your Folding@Home performance.
The 7850 also outperforms the 560Ti.
http://www.anandtech.com/bench/Product/549?vs=547

Here's the card I recommend.
Sapphire HD7850 1GB. $175 ($10 rebate)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
or if your willing to max the budget, the reference 2GB model of the 7850. $210 ($15 rebate)
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

How many connectors it will require depends on the card. But the 7850 I linked above takes one 6-pin connector, while a 560Ti requires two.

If you can afford the Asus GTX560, you'd be better of with AMD 7850 1GB card (or maybe the 2GB version as well if there's a great deal).

If you only want to spend around $150 however, the best choice is the GTX650ti (faster or similar than a 560 without high AA and lower power consumption)