g3 500 vs. pIII 900 (Score 1)

I am looking at a ibook and a dell. Anyone know what which processor would be faster in compile times? I would be using my laptop for a lot of sw development, ie., comp. sci homework :) . I know that you can't directly compare clockspeeds across architectures, so just wondering if these two processors are comparable.
Also, is is possible to upgrade the cpu on laptops? iBooks? Dell inspirions?

~SQL