Quick Question

Nope.

If you're planning to get a 560, better get a 6870. It's cheaper.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

$150 with promo and mail in rebate.

No bottleneck. If you have a look over at 3dmark results though you will see that the 6850 and 6870 paired with the i3 2100 have very similar performances and no real stepping. The 560 is similar to the 6870 but give it a search, see which combo benchmarks better.

That proves a bottleneck vx53c. If you put in a faster card and the score doesn't go up, its being held back by something. In this case it might be the CPU, but ram or software is also possible.

A 2100 is a semi weak CPU and I can see it holding a GPU back in games that want a strong CPU. You might want to see about getting the 2400.

If you go with Intel that is the best option for that price, if you want to step up to an i5 that would be far better as the i5 can be overclocked where that isn't an option on the i3. Another route you could go would be a phenom ll X4, the 955 that is 3.2GHz stock and can easily be overclocked to match the i3 and beat it in some cases.

The i5 2400 is also good without overclocking needs

If you 're about to get the crappy dual core i3, do yourself a favor and get Phenom ii x4 955. If you want to go with Intel look at i5 2400 or better

Yeah, what he said. ^