I'm trying to upgrade my parents' computer from XP to Win7. They have the Win7 home disc. Normally I would just go into the BIOS, change the boot priority to the DVD drive, and boot into the disc. For some reason the DVD drive isn't showing in the BIOS though (e: it's listed under a hardware menu, but not in the boot priority menu). It's an LG connected by IDE. I'm given options for floppy, hard disk, ls120, cd, usb, etc but not DVD. When I choose CD, it prompts me to press any key to boot into the disc, but nothing happens when I press a key and the computer just starts normally.

Originally there were 2 disc drives connected with the same cable, but I unplugged one and made sure the remaining one is a master.