Megahertz don't matter.
An articule on the Producer Price Indexes pages says that the Megahertz rating is "more confusing than enlightening" and appears to support AMD by saying that one chip running at a particular MHz rating can easily outperform other chips based at the same MHz.
And it calls for objective benchmarketing to steer your way through the maze. Well, we'd all like that, wouldn't we.
It points out different architectures give different results anyway, making the process harder, and underlines its conclusions by saying that other elements of a PC have vastly incresaed in performance anyway.
The article begings to lose us a bit when it starts talking about "hedonic modelling" and introducting very scarely looking equations like the following, but hey, we're just hack journalists here.

Go here for the musings of the Department of Labor. ยต