[BlueSkyJaunte]

Basically the Centrino uses the old P3 core whereas the P4 has a "newer" core with a very deep pipeline.

This is useful if you're doing certain types of things like multimedia. It sucks for linear-type computation.

For example, my job is mostly discrete event simulation. I won't explain in detail, but it's a very non-parallelizable (is that a word?) computing task. Every time step is dependent on the previous time step's events.

We have a lab full of machines that we use to make simulation runs. Our P3-800MHz machines were only 5% slower than our brand-spanking-new (at the time) P4-1.7GHz machines. Very disappointing.

I think the P4 core was more easily cranked to higher clock speeds, since that was the marketing benchmark. So Intel pushed the P4. However it sucks tons of power and has the problems explained above. The newer P3-based core (Pentium M) is faster clock-for-clock and they've worked out the heat issues. Plus, GHz no longer sells that much since these computer things have become commodities.

Just one observer's semi-educated opinion...