If you don't have OS 9 already installed, then the only installation will be a Clean Install, I guess that is what your choice is. If OS 9 was previously installed (should have shipped that way, Have you reformatted so that OS X is the only operating system installed?), then the clean install will leave the previous OS 9 mostly intact, but disabled, so you can transfer old settings, etc. Once you have OS 9 the way you want, then you can delete the Previous System Folder