Prairie Group's Support Determining if Classic (OS 9) is already installed. Double-click on your OS X hard drive icon to open it. You will see a folder named "System" which is your OS X operating system. If you have Classic installed, you will also see a folder named "System Folder" which is your OS 9 operating system. Note that the OS 9 operating system actually has the word "Folder" as part of the folder name. Installing Classic on an OS X Computer that is missing OS 9 (Classic) Note: Classic can be installed on all OS X computers except the Intel-based computers released in January 2006 and any running Mac OS X 10.5, Leopard. 1) Original OS X computers came with Classic pre-installed. If you need to re-install OS 9, see the section at the bottom of this page. 2) Later Apple stopped pre-installing Classic, but included a CD labeled Classic. This is the easiest. Just insert the CD labeled Classic and follow the onscreen instructions. 3) Still later Apple included Classic on Install Disc 2 as a part of the overall OS X installation discs. The following is from page 56 of an iMac user guide. Your iMac G5 does not come with Mac OS 9 installed. To use Mac OS 9 applications with your iMac G5, you have to install Mac OS 9 using the Mac OS X install Disc 2. To install Mac OS 9: i) Back up your important files, if possible. [This is a standard precaution whenever installing any software.] ii) Insert the Mac OS X Install Disc 2 that came with your iMac G5. iii) Double-click "Install Mac OS 9 System Support." iv) Follow the onscreen instructions. v) After selecting the destination disk for installation, continue following the onscreen instructions. Re-installing Classic on an OS X Computer that has a damaged OS 9 (Classic) This is more complicated. You should read the information provided by Apple. http://docs.info.apple.com/article.html?artnum=106294#m9