The Pentium 4 M is indeed the mobile version of the P4. Top spec is 3.2GHz, 533MHz FSB, with Hyperthreading.

The Pentium M is a different and much more efficient architecture. Top spec is 1.7GHz.


The P4, due to its high power consumption and heat output, isn't really suited for laptops, even in P4-M form with power saving Speedstep technology. It is thus mostly used in large 'desknotes' these days.


Price-wise, the OEM price for a Pentium M is about the same as for a Pentium 4 with double the clock speed.

Performance-wise, one could say a P4 needs, very roughly, 1.5-2 times the clock speed to achieve a Pentium M's performance. The P4 is especially suited for encoding video stream, hardly the most common use for a laptop.


In short: you want a Pentium M 1.7 in your new T42