It turns out that Apple has known for a long time that the Mac OS X installer will damage the old iMacs that don't have OS 9.1 and the firmware upgrade. However, Apple wants to sell new Macs and what better way to sell new Macs than to break the old ones. In all the years OS X has been out Apple could have added the following to the Mac OS X system requirements, but they didn't!
"Mac OS 9.1 and latest firmware upgrade."
If you want to understand this problem go to the links shown below. I followed all the steps shown on those pages and in the end the iMac would not boot.
http://www.capecodgraphics.com/imac_firmware.htm http://www.macosxhints.com/article....021023065837185
Just last week I had people who sell Macs, while reading the Mac OS X system requirements off the retail box, tell me that the Mac OS X upgrade to a 400 MHz G3 iMac DV running Mac OS 8.6 would not be a problem.