The idea of one drive and separate OS is a good one, although I'm a bit reluctant as a PC novice. However, a useful advantage of physically separate drives is isolation of viruses and irretrevable (by me, anyway) crashes.
And yes, I'm not looking forward to reinstalling everything on three hard drives.
That raises an interesting point. Some time ago, I was disappointed to find that you even need to reinstall everything when you move to an identical computer in every respect --- same motherboard, RAM, graphics card etc. The hard drive refuses to transfer over, even though it is sitting in an identical computer. No doubt there's some ROM (?), or whatever, that is different, but I'm just guessing.