Do you have any other working CD-ROMs around that you could try out in the system?
If you do give them a try if it works then the problem lies with the cd drives. If not then you have to go through a process of elimation to find where the problem is.
Have you checked your IDE channels in device manager to verrify they are both working correctly? If there not then thats where the problem is and that means a new mobo.
If they are try a different IDE cable.