processors that work with each other [with properly written software]. Seems obvious that two working on different parts of the problem at the same time and then putting them together with the answer pays off.
The idea that the clock speed of the CPU equaled performance was false has been proved for a few years by the AMD CPU's out performing Intel CPU's that ran at much higher speeds. It got so bad that Intel about 8 months ago ceased including the clock speed as part of their CPU model number.
The generation of Intell CPU's just now hatching will run at lower clock speeds but perform as well. The biggest problem with clock speed is that it causes the CPU to get extremely hot. Intel's CPU's got over a hundred watts, thus when they decided to go to Dual Core they couldn't use the top speed ones in Dual because they simply couldn't cool them.
It is the total architecture of the design of a CPU, its chipset and cache that determine performance.
How does having a dual core CPU help? I look at them on Newegg and they don't have any higher speeds than the other ones... At least not that I saw. Some were only 2.0ghz. So... What's so great about it?