There is no single industry-standard method of measuring the performance of a processor, since chips with the same clock speed may deliver different performance levels depending on the application. Intel's own 1.7GHz mobile Pentium 4, for example, delivers roughly the same performance for productivity applications as a 1.2GHz mobile Pentium III.

Yeah, good luck getting those two guys to agree on an industry standard for measuring speed. Btw, there's a story floating around of a price drop on both sides around the end of this month.

update: Here's a bit more on those price drops. Thanks Tech-Report