Hey all,
If your planning on using Mac OS X, the G4 will work better.....
Here's an interesting comparison....
I have a 867MHz G4 Quicksilver tower and a 600MHz G3 iMac. I became addicted to American McGee's Alice by Aspyr. Believe it or not, with its original configs, the iMac wth 256MB RAM would load the game faster than the G4 with 128MB. Then again, when I added a 512MB stick of Crucial RAM to the G4...well...that ended all comparisons between that and any other machine around the dorm! I know the ram was a bit excessive, but it shows a point of how you could try to compensate. Also consider that some of the TiBooks only ship a 133MHz bus on the 667MHz model, the rest are 100MHz. Most iBooks have been bumped up to 100MHz, with the low end at 66MHz.
I prefer the G4 processors. Very strong. The iBook seemed to be more fun to use from my experience. Sounds odd, but it's true. If your not doing real intensive stuff, get the iBook and use some of the extra cash to get a RAM upgrade on it. Either way you can get a combo drive now!
Lemme know what you decide or if I've managed to completely confuse you!
Mike D