Recently I reinstalled the complete system. I reformatted the disks of both OS9 and OSX. Since I never used OS9 anymore, I didn't check the option to be able to install OS9, because I thought I didn't need that.
Of course, now I do

!!! I know I can erase one of my two drives, repartition it, and then select that option, but that's a real pain in the

, because I then have to reinstall OSX again, and do a lot of work because not everything fits on the other drive.
Are there more options? Is just erasing the disk using disk utility enough? Will that make it possible to select the checkbox that is now greyed out?