last model Power Book that can boot OS9?

It was the last of the Titanium PowerBook G4. The 1.0 GHz model.

http://www.everymac.com/systems/apple/powerbookg4/stats/powerbook_g41.0.html

Paul: The 867MHz and 1GHz Titanium Powerbooks were released and discontinued at the same time. They were the fourth and final generation of Tibooks, produced from Nov. 2002 through September 2003. They can boot only into the machine-specific build of OS 9.2.2 that was shipped with them. No retail or other model-specific build of OS 9 will start them. If you're shopping for an OS 9-bootable Powerbook and find one of these models, be SURE to get the original Install/Restore DVD that came with it. NO other disc can install a bootable OS 9 on it.

Hi,
For a list of what run on what, check the mothership...
http://docs.info.apple.com/article.html?artnum=25114

A+

eww has the definitive answer. And because of the 1GHz being the last and fastest, they usually carry a price premium, well they did when I went looking for one a year ago.

There is also a simple rule of thumb for getting an OS9 bootable PowerBook, Titanium powerbooks boot OS9, Aluminium do not. Titanium powerbooks take original AirPort cards and have the ports along the back, Aluminium powerbooks have AirPort Extreme and have their ports down both sides.

Again like eww said, whatever model you get, make sure you get the original discs with it, OS9.2 was around for a very long time before being canned, so a lot of computers need their original restore and install discs rather than a retail OS9.2.1 disc.

For use with Mac OS 9, even the first TiBooks are pretty fast. Those came with 9.1, and did not even include Mac OS X. A true G4 Mac OS 9 machine... 😉

Yeah, I ran out and got a 500MHz Titanium PBG4 the week they came out (to replace an old PBG3), OS9.1 and NO OSX, I was a little miffed.