b, this drive is the drive one you partition with Bootcamp Assistant. Windows must be on this drive. Then you can add an SSD but not for Windows. Then you can do what you want with c and d.
thanks for the reply, Bob! unfortunately your reply is a bit cryptic, and i don't really understand - could you perhaps clarify?
you also mention putting Windows on my OS X boot drive, but that is not what i'm doing. to be clear, here is my intended setup:
optical drive compartment: OS X boot SSD (but wanting to replace with higher capacity SSD)
bay1: SSD (blank at the moment) - for dedicated use by my Windows install
bay2: HD with all my Mac Data
bay4: HD for time machine backups
He's saying that your plan won't work. Windows must be installed on the same drive as OS X.
i'm not sure that is accurate. i've seen references on this forum of Mac Pro folks using a dedicated drive for their Win 7 installs.
Apple says in their FAQ:
"Boot Camp Assistant creates a second partition on your existing startup disk for the Microsoft Windows operating system, or allows you to install Microsoft Windows on another drive if you have more than one internal hard drive installed."
And "The Hatter" (a frequent poster on this forum) recommends a dedicated drive for windows in this thread: