I also went from a 12" 1.5 PowerBook to first, a MBP 1.83 then finally a MacBook 2.0. Both the MB and the MBP literally walk off and leave the PB 1.5 in performance. Of course, routine tasks like Safari, Mail, etc. are about the same, but more intensive tasks don't even compare. For example, using Handbrake to rip a DVD, nearly 2hours long took about 4+ hours on the PB. The MB ripped the same DVD is about 35 minutes. Absolutely incredible power we have now, guys.