I have seen a few mention where specific software is located on their editing station. On my new build, I have 4 internal drives - 1 of which is a 10K drive for capturing. So 3 are available for everything else.

Should I put the operating system and Vegas on one drive, raw data on the second drive, and rendered files on the third? Is this the most efficient/reliable configuration?

yes. put the OS with whatever programs you use on 1 drive, capture to another and renders to a 3rd although that maynot be 100% necessary. You could actually use the capture drive to render to.