AMD/Intel Difference

There is a difference in architecture which is the reason and it is to long to list here.
http://www.amd.com/us/products/Pages/processors.aspx
http://www.intel.com/?en_US_01

Intel architecture is superior to AMD.It takes a six core Amd cpu to come close to performance of quard core intel i7 cpu.I think that enough to tell who is better.

Here is a good start http://en.wikipedia.org/wiki/X86
They are usually a good source of information.

Yeah but AMD compensates the lower performance with lower price.

Anyway if you want the best, fastest CPU's, then the Core i7 series are your best bet. AMD is more orientated to budget CPU's (they have better price/performance ratio)

StarCraft II only takes advantage of dual cores, but still processing power plays a major role in this game. For example, the Core i3 540 processor only has half the L3 cache of the Core i5 750 and this makes the latter 27% faster when comparing the clock for clock data at 3.70GHz.

The extra threads of the Core i7 920 processor are no advantage when compared to the Core i5 750 in this game, but the additional memory capacity and bandwidth is. The Core i7 920 was 11% faster when comparing the clock for clock data at 3.70GHz which is quite significant.

An older processor like the Core 2 Quad Q6600 suffers compared to the other CPUs tested, serving as a bottleneck to a high-end GPU such as the GeForce GTX 480. The Phenom II processors delivered average performance and we saw no real difference between the Phenom II X2 (dual-core) and Phenom II X4 (quad-core processors).

It is a shame that StarCraft II can only utilize two cores, as this really hurts older quad-core processors such as the Core 2 Quad Q6600. Furthermore this will also mean that those with budget quad-core processors, such as the Athlon II X4, will also suffer.