An iMac computer can run into disk troubles that make it impossible to boot from the hard drive. If this happens, it is possible to boot your iMac from a CD, as long as you have a bootable CD that can fix your iMac. While all iMacs come with the installation software as bootable DVDs, it is ideal to have a backup version just in case. You can make a boot CD for an iMac easily as long as you have your original installation DVDs. Warnings Writer Bio

How to Make a Boot CD for an iMac - 58