It sounds like your CD/DVD drive is not selected as a bootable drive in your BIOS settings. I don't know how your bios is setup exactly, but there should be something like BOOT SEQUENCE or BOOT DEVICE PRIORITY or something similar to that. Usually it would go floppy (if you actually have one), CD/DVD drive(s), and then hard drives, and some now have flash memory drives as a selectable bootable drive. You need to make sure that you CD/DVD drive is selected somewhere in one of those settings.
If all of that is setup correctly the I would check to make sure that the disc is actually bootable. If the settings are right and the disc is bootable then the harddrive might need to have a full format, as oppoesed to a quick format, to install vista. I say this because I had a problem with my harddisk not being formatted first before trying to install.
If none of that works then I can't imagine where the problem would actually be. Hope this helps and solves your problem.
I just replaced a EIDE hard driver in my computer for the OS im installing vista ultimate. When i go to put the disc into D drive i am getting a message reboot and select proper boot device or insert boot media in selected device and press a key. when i do this same message continues to appear. Please advise what am i doing wrong or what maybe i can do to correct this problem. thaks