Check the BIOS settings under the Standard Setup (or similar name) and ensure that the channels in which the drives are connected are set to "Auto". Near the bottom of your screen, within the BIOS setup program, you will see the various keys to use to navigate around within the setup program.
When you boot the computer up, press the Pause key at the point where it shows the BIOS Summary screen. This shows you all the stats of the system and the IRQ settings for devices below it. It comes up after the system has sun the memory tests and detected the IDE devices. Ensure that the devices are being seen properly. If they aren't, then do as Huge said and reseat the IDE cables. Also, just for testing, you might try connecting them to another channel, although I'm unclear as to how the devices are currently arranged. If they are connected to the secondary channel, then connect them to the primary. If one of the devices is on the same channel as the hard drive, then disconnect the hard drive and see if it gets detected by itself. If it's possible, replace the IDE cables with new ones and test again.