@Hungry Sean
Performance is complicated...
...but a 5Ghz core 2 duo would wreck an i7 at a great many workloads.I think global compute resources have diverged enough that there is space for three different types of x86 CPUs.
Small low power many thread doohickies, good for lots of little programs or web servers. Would make good netbooks, laptops, and maybe would be useful for application virtualisation.
Slightly more beefy midrange things with a moderate (4-8) threads for folks doing some heavy lifting. Rendering, A/V editing or VDI.
Screamingly fast per-thread low core count (2 cores?) designed for workloads that need the straight-line speed and don’t multi-thread well.
http://arstechnica.com/old/content/2002/10/hyperthreading.ars/1
The above is an article well worth reading on the topic. I think the complicated nature of performance means that the public’s “obsession” with Mhz isn’t necessarily wrong. Architecture and attempts to parallelise can only get you so far. There are still plenty of compute tasks for which what you really need is a bloody big bit cruncher going at as high a clock rate as they can make ‘em.
Put more simply: CISC !> RISC for all workloads.