In the case of the Macintosh pricing versus PC pricing, the errors have led to the general impression that comparable PC's are cheaper than comparable Macs. Now, I won't debate whether or not that's always been the case, but I will state categorically that it ain't true today and hasn't been for the last 2-3 years.
But folks like my friend keep doing their careful analyses, and similarly misguided journalists duplicate their work in a forum for the whole world to see. It doesn't take too many of these to drown out the dissenting voices like mine, who keep saying, “But wait a minute… Didn't you know that…”
The first fundamental error most people with only a superficial understanding of computers make is that the speed specifications published for Intel-based PC's are directly comparable with the speed of RISC (reduced instruction set computing) chips like the ones Apple uses, either their G4 chips from Motorola, or the newer G5 chips from IBM. They aren't.