I was considering upgrading my CPU in My P5E and run an image of the
original Boot Disk (in my case an XP3 System HD) and If all else failed.
I would put the original CPU and HD back on my mobo and get back to
SQUARE ONE. Would this be a plausible solution?

But Now I find that I would have to upgrade my BIOS for the CPU I
received. which makes things even thornier. So I am considering have a
Backup P5E to be placed on order to replace the original board if my
mobo should crash and burn. The new P5E might presumably have the newer
BIOS upgrade or at least different from the Revision I have now. (Not
sure If I would want to venture soldering in a new BIOS chip to recoup
my failure.)

So The MAIN QUESTION IS. If I upgrade my BIOS and the original mobo
craps out, would I be able to get the exact same model with the same
BIOS REV or a newer REV for that matter and attach the original boot
disk and CPU, and THEN be back to square one? I would plan on writing
down my BIOS settings before doing any of this and entering them before
reattaching My original System disk and CPU.

I know you can't switch out different types of Boards with your
original system disk. But you could change out your Ram and perhaps your
CPU, right? Any clarification on these issues would be appreciated.