Looking at the
Latest PS7Bench results from Ars you can pretty clearly see that even a 1.25 and 1.33 GHz PowerBook G4 doesn't do too well... on par with a 1.6 GHz P-M Dell D800 and slightly slower than a 1.6 GHz P-M IBM T40. (Still, it's not toooo horrible, considering how efficent and powerful the Pentium-M is at its low clockspeed).
But based on my own experience with my 1.25 GHz PowerBook G4, I can tell you that it does indeed work very well with iMovie and iDVD for editing and burning my home videos. And that's with my 4200 RPM drive! But keep in mind that each DV stream only requires 3.125 MBytes/sec.
I can also tell you that Photoshop CS. zooms on this PowerBook for the light duty home photos (3.2 and 5 Mpixel) and web resolution (800x600) jpegs I work with. Even though a dual 2.5 GHz G5 benchmarks more than 3x faster than my PowerBook at Photoshop, I probably wouldn't notice a huge difference because each of the filters I work with generally takes less than 1 second to complete anyway, many occur instantly.
For what little gaming I do on my PowerBook, I have also found it to be more than satasfactory. X-Plane, Enigmo, World of Warcarft, Halo, and UT2004 all work great, especially after the OpenGL updates in Mac OS X 10.3.7. (But gaming is something I generally do on my desktop PCs. Gotta have my HL2 and Doom3! And gotta have real desktop performance on a sweet 21" CRT!)
Basiclly, I feel that a 15" or 17" PowerBook probably offers far more power than most of its users would currently need. The fit and finish, in my opinion, are worth the cost. As a PC user, I bought mine out of curiosity and after being discouraged by most of the plastic PC notebooks I tried. Using an Apple has been a learning experience, but I have really enjoyed it and I would buy another PowerBook in the future, even at the current price. But I'm also a hardware geek and I wish IBM and Apple would get the G5 into the book ASAP! And my next purchase will be an updated PC first!