"...install both a DVD Rom, and a CD writer as internal drives..."
Set one as master and the other as slave - it doesn't matter which for optical drives. Actually the terms are a misleading - the only difference between M and S is which one the BIOS sees first - that's why you"ll normally set up your main hard drive as master.
Today's IDE controllers on modern systems support running the master and slave device at different speeds (independent device timing), so the old canard about not putting an optical drive on the same channel as your main hard drive falls away.
FYI - Cable select requires a special cable-select cable (pin 28 on the master channel carries the CSEL signal whereas pin 28 on the slave channel is open circuit) - the drive thus "knows" which channel it's on and configures itself accordingly. Cable select on the old 40-conductor cables was never standardised, often didn't work and never really caught on.
Current 80-conductor IDE/ATA cables (80 because of separate grounds to reduce crosstalk & noise) _should_ all support CS - personally I don't bother and hardwire the drives as fixed M or S.
Suggest you don't use CS.
PS: For 2 optical drives on one IDE channel 40-conductor cables will work fine most of the time, but you can use 80-con if you like - note that you should always use 80-con on the channel you have your hard drive/s on.
Tip: If you use a removable hard drive in a "sled" or "caddy", set it up as slave on an IDE channel with an optical drive as master. Unlike hard drives, optical drives don't really care whether a slave is present or not, so you never have to change anything.
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