I find the most reliable way of testing optical drives is to make sure the BIOS boot order is DVD first, get an OS disk (bootable) and see if the machine will boot from it.
This way you can discount the OS from the equation.
If it dont boot and the BIOS is set correctly, and the disk is definately bootable then the only thing left to check is the IDE/SATA cables/ports.
Failing that, the drive is dead.