Throw in the Intel i5-3550 and 3570K CPUs with Win7 and Win8 and see what the numbers say... wouldn't that be fair to see the difference as well?
Yeah, if you already have the board and memory, its mostly logical. But for someone going for a rebuild... it is not, especially if you live near a Microcenter.
I paid $190 for my i5-3570K CPU, $90 for my Z77 gigabyte motherboard which out-does AMD 900 Series boards. Z77 have native USB 3.0, SATA 3.0, PCIe 3.0... AMD doesn't have PCIe 3.0 until 2014. And unless you get an A-Series CPU, you don't have native USB 3.0 either.
This, an AMD boards are a bit more costly and more complicated.
The OTHER AMD problem is that they are packaging clean CPU coolers with their CPUs... they are loud!! So add $25 for a good replacement. The extra costs for electricity doesn't help.