zoran said:
In the superdrive slot? How? An ATA drive?
Apple designed it so that the 4 HDD bays were SATA connectors on a 'backplane'. This is getting pretty common for high-end equipment, as SATA connectors are better for this type of use than PATA, and there is definitely more demand for things like hot-swap drive bays.
However, using SATA for the optical bay is overkill. Apple wired up the two optical bays to older-style IDE buses which helps isolate bandwidth, and I think it might save em a few pennies on cost of parts, and maybe a couple bucks on the drive itself. Just go about your business as if you are going to install a second optical drive, but put a PATA drive there.
Sounds like you have existing drive(s) you want to keep around. Am I right? If I am not, then you really should consider investing in SATA moving forward. The cost difference to the consumer is getting to be about 6-10$, and the better performance is usually worth it.