I have an iBook 600MHz G3 and I don't understand people when they say that it will not run OSX well. Mine runs it quite snappy. Window resizing is fairly smooth and the dock works well. Apps launch quite fast. I admit that I run only consumer based programs, MS Office, Appleworks, iTunes, iPhoto, iMovie, Mail, IE, etc. I would suppose that some programs that the pros use might lag on the machine, but isn't that the reason they build the TiBook? If the iBook had the same processing power as the TiBook and was priced the same as iBooks are today...who in the hell would fork over the cash for a bigger display? Maybe a few would, but I would imagine it would undermine the sales of the TiBook drastically and hurt Apple profits.
I finally got a chance to play with the new iMac today at the Apple dealer. Very impressive machine to say the least. My buddies were with me, MS fans, and they too were totally impressed. Yes it did feel more responsive then my iBook, but not as much as what I was expecting with all the G4 hype I hear on these message boards. Apps launched just slightly faster...the only real improvements I could see with what I was doing was smoother window resizing and a Quicktime movie would minimize with less distortion and lag...but even with the 800MHz G4 it was still noticable. While working in programs...little difference was noticed. If my iBook ran at 800Mhz like the iMac does...even with the G3 it would hang right in there.
I will not argue the fact that the G4 is better...but to say a 600MHz 750cx will not run OSX is absured to say the least.