Depends on age of system!!!
Some older systems do not support booting from CD or DVD, and for these systems you may need to boot from floppy. Laptops were the last to follow this boot ability. I have some older Toshiba Pentium II and early Pentium III systems that do not support booting from CD.
Most systems 8 years old or newer support booting from CD Rom after post. You may just need to edit the boot order in the bios to be CD before HD.
