Hi kansasjhawk and welcome to Windows 7 Forums
That's a strange one.
Normally, if you have a bootable OS disk in the drive, and the drive is higher up in the boot order set in the BIOS than the HDD, then a message will appear asking if you want to boot from the drive, and to press any key if you do, failing which booting will continue with the next device in the boot order. The actual order doesn't matter normally, unless you specifically need to boot from floppy or CD/DVD.
Just out of interest, what interface do your HDD and optical drive use (PATA/IDE or SATA)?