Best choices for low power consumption / high battery life

hello,

This fall I'm beginning to study master's course, and I'ld like to get a laptop to use while commuting, cause my new school is about 1.5 hours away from my home.

The most important points for me are, low power consumption, size & weight, a low profile generic graphics card which will work with any OS I throw at it (including weird linux distros). I will not be gaming at all with this laptop, except the occasional online spades if I setup an XP.

So, as for the CPU, I think a low spec Pentium M is what I want. But I'ld like to know if previous pentiums are worse or better than a centrino. I believe even a pentium II @ 400Mhz will be enough for me.

also I'ld like to know how Pentium M compares to PPC laptops in terms of power consumption. a mac power book with a G3 will also prove quite interesting for me, especially after the price drop after apple announced the crossover to intel processors. I'ld like to hear from people who have experiences with mac powerbooks if possible.

thanks !