I have two hard drives in RAID (bios Configure SATA As: set to RAID). I had an optical drive also on SATA and the windows xp 32 device manager showed the drive with an exclaimation point next to it so I tried a PATA optical drive thinking that might change it but it hasn't. the drive still doesn't show up in windows. I imagine it has something to do with the IDE being set to RAID instead of IDE but I'm not sure.
The mere fact that you have two HDD's set up in a RAID array should NOT prevent a third SATA device from working as a non-RAID device. Did you check in your RAID Management screens to verify that only the two HDD's are assigned to a RAID array, and the third SATA device was being used as non-RAID?
Anyway, now you have an IDE device for your optical drive. To use it you need to set a few things correctly. On the drive, its jumpers MUST be set to the Master position, since obviously this is the ONLY IDE device on that one data ribbon. Then it ought to be connected to the END connector. A ribbon cable with three connectors is normally used with the BLUE connector to the mobo port, the BLACK connector on the other end to the Master device on this port, and the GREY connector in the middle to the Slave device if there is one. Master and Slave refer only to that one IDE Port you are using, NOT to the whole machine and all its devices.
Secondly, you must check the BIOS Setup screens to verify that the IDE port you are trying to use actually is Enabled and set to Auto-Detect devices on it. The BIOS should show you right away whether it can detect that hardware. If it can then Windows OUGHT to be able to see it and use it. If Windows can't "see" a device that the BIOS does see, then Windows has a configuration problem. Actually, in your situation I would suggest that you disconnect the new optical drive, boot the machine, and go into Windows Device Manager and find any reference to the old SATA optical drive and Remove that device. Shut down, make sure the old SATA optical drive is disconnected, and connect up the new IDE optical drive. Boot up and let it find that new device and get its drivers set up so Windows can use it.
Now reboot and go directly into BIOS Setup again. Look for where you set the Boot Priority Sequence. Most people would choose to set it to boot from the optical drive as first choice (it will only show up as a possible choice if the BIOS does recognize it), and the RAID array as the second choice. Set it as you choose and Save and Exit.
See if that gets your optical and RAID units working.