A few corrections
As stated in an earlier reply by some else, but with a lot more bias, you're wrong.
The new AMD kit is a mere $5-10 premium over the "on sale" i3-2100. If you compare vs the i3-2105 (with the HD 3000 gfx, rather than the very worse HD 2000 of the original i3-2100), the price matches exactly.
Platform is also a consideration, since the A75 boards, when features are compared, are generally cheaper than their 1155 counterparts. Not by much mind you.
Also, as a correction to the biased reply, it is true the i3 is a dual core, with hyperthreading, however, hyperthreading gains a lot more than a mere 10% (the OP stated "2.2" factoring in the dual cores) performance increase. There's upwards to a 40-60% increase in threaded situations over running with hyperthreading disabled. What was never touched was that the i3 cores, MHz-for-MHz perform better than the AMD cores.
In the end, the i3-2105 (yes, better GPU than the 2100) has better performance in single-threaded or general light loads. The AMD A8 chip does better when you're taxing the system with heavily-threaded loads (does better by far btw). However, you're not likely to do that unless your encoding video or doing many things at once, at which point, you bought the wrong CPU either way. The GPU core in Sandy Bridge doesn't even hold water against the A8 GPU core. The A8 has 2x the performance of the HD 3000, hands down. There's just no comparison. The only advantage the HD 3000 has is QuickSync. But then again, the A8 has DX11.
Who's the victor? Anyone who buys the $500 Walmart machines. Why? Because they'll have an AMD CPU.