Hi,
I just went through that decision and went with the 867 12" powerbook. Though, looking back I may have done it differently. A few things to note;
1) The 867Mhz has 256k L2(?) cache, so the 14" ibook is the same
2) The Powerbooks don't come with Appleworks
Either way though. I'm not upset about my decision. Its still a great computer.