If you are using just the motherboard ATA Controller then you won't be able to put any device on it's own.  You have to remember your hard drive has to be included in the setup.  That means you will have the hard drive and a CD device on one IDE port and two CD devices on the second IDE port.   Generally it is not recommended having a hard drive and CD device on the same IDE port as it may decrease performance.  An alternative would be to install a ATA Controller card in one of your available PCI slots.  That would give you the ability to hook up 4 more IDE devices for a grand total of 8 devices for your machine.  This will allow you to put the hard drive on it's own IDE port as well as spreading out the CD devices.  If the day comes you want to install another hard drive you can slave it to the existing one provided you have room in the case.

D'oh! You see... it HAS been awhile since I opened up the case. Yeah, I forgot about the HD. I generally figure this stuff out as I go along, but after the "job" is done, the how-to's seem to make a beeline for the exit door in my memory.

Thanks for your response and advice. Looks like I'll be getting an ATA controller card. Thanks again!