I like to think of these cpus as engines and these cores as cylinders. I like to think of Ghz as gears and how the higher the gear your on, let's say 2.4Ghz (2nd gear), vs 3.0Ghz (3rd gear), or overclocked to 4Ghz (4th gear). Just because your on a fouth gear with a shitty engine, doesn't mean it's going to go fast compared to a third gear i7 cpu which has a ton of horsepower. Well that's the concept anyways, a single core even though it doesn't have dual cores, cylinders, also doesn't have anywhere near the horse power of a dual core. Just as a dual core doesn't have the horse power or cylinders to compete against a quad. To confirm the horse power, just look at cpu benchmarks, you get more frames out of games and stuff and a more powerful cpu like a quad will be higher than a dual, which is higher than a single core which is really acient relics no one should use anymore.
About hyperthreading, it's like faking or simulating more engine cylinders, sort of like what the i7 processor that I use does, simulating 8 hyperthreads or cylinders. You see alot of core2 quads, they are just dual cores with hyperthreading.
Here is an interesting fact, the six core phenom runs slower than the X4 phenom. Why in the world is it like that? Well it has to do with horsepower, some cpus are stronger than others, like a stronger engine overall going back to my horse power theory dispite having less cylinders. Having more cylinders doesn't mean it's better, the i7 4 core 8 hyperthread is much stronger even if I ran it on third gear, it would smoke both these cpus horse powerwise, even if you try to bring it up to the 4th gear, it will still edge out these amd cpus.