I bought a used ibook G4 last year that came with 10.5 installed. I want to switch back to 10.4 but when I tried to install with 10.4 discs, I got the error message that I can not install this system on this computer. the Mac is a 1.33 Ghz PowerPC G4, so I should be able to install 10.4. Is there something in 10.5 that I need to do first?? _________________________________________________ DJ Fern Firefly Entertainment~ Creating The Soundtrack For Your Celebration DJ and Event Planning services for all occasions. _________________________________________________