Well, which iMac are we talking about here? According to http://support.apple.com/kb/HT1835 and http://support.apple.com/kb/HT2191 , not all iMacs that can run Panther can run OS 9.
You may also enjoy http://lowendmac.com/misc/08mr/compl...-mac-os-9.html . And perhaps http://www.os9forever.com/ .