If the boot sequence is right,

If your PC's boot sequence is right, it should be able boot from the CD you made because it can start auto-run. I think the possible problem is that when the PC is booting from CD while the hard disk drive has existing OS, it has only 3 seconds time for you to press the key to make it boot from CD (screen display "press spacebar to boot from CD"), otherwise it defaults to hard disk. So when you boot from CD, look at the screen, do not miss that message, and press the spacebar in time.