I would like to know the full release date of Mac OS X 10.5 and the system requirements. The fastest Macintosh machine in my house is my Power Macintosh G3 B&W running at 450 MHz. I am thinking about upgrading to a G4 if OS 10.5 will not run on a G3. My next computer will probably be a Mac Pro. If anyone knows the release date and system requirements, please tell me. Thank you.