Well why waste a functioning Hard drive? yes a samsung spinpoint SATA 250gb and 80Gb Seagate Barracuda SATA (might drop the barracuda) will be going, having the IDE in there for back up/storage, if the SATA disk dies then you still have the 2nd disk.
Personal experience is that Hard drives are one of thoes things that can die (I've found overheating is often the cause and is fatal)
Ram dies, it's annoying but not too great a fuss
Motherboard dies, bigger headache but livable if still under warranty
Hard driver dies, major headache trying to recover lost data.
EDIT: I also agree about both off for the inital install, but after that?
Again, it's not for me, if it was I'd have no qualms about juryrigging something or takeing sharp bladed objects to the trays to make them work the way I want them too.