Geek Patrol benchmarked a MacBook Pro and a PowerBook G4. Not surprisingly, they concluded: "The MacBook Pro outperformed the PowerBook G4 in almost every benchmark. Since all of the MacBook Pro's baseline scores are over 100, it even outperformed our baseline system, a Power Mac G5 1.6GHz! The only benchmark where the PowerBook G4 outperformed the MacBook Pro, Stdlib Allocate, depends more on library performance than raw hardware performance. If you're upgrading from a PowerBook G4 (or even an early Power Mac G5), you'll certainly notice how much faster the MacBook Pro is, especially with multi-threaded applications."