2 Drives, 2 Operating systems

I have Win XP on my master drive. I have cleaned out my 2nd drive and want to install another OS. Do I have to make the 2nd drive master whenever I want to use this OS? Or is there a way for both to be master and just switch boot sequence when I want to boot the 2nd drive? Or would I need to set both to cable select?

I should have partitioned first drive, but never thought I would be adding another OS.

Thanks in advance for any and all help.