@Greg Shultz: Thanks for the follow-up Greg!
No inconvenience - not for me anyway. Not yet. Just good to know the details about the hardware platform that was used for the upgrade. You know how us techies can be....detail oriented and frequently comparing hardware.

So, the Upgrade Assistant can detect the previous Windows version installed on the system and then do a "1 for 1" type upgrade: W7 32-bit for W8 32-bit or W7 64-bit for W8 64-bit. Seems straightforward.
Also, thanks for posting the links to the articles about dual boot. I think I'm going to give it a try. Problem for me is that I don't qualify for the $15.00 W8 upgrade. I have a "newer" system with W7 64-bit but it was purchased before June 2012. So, I guess I'll have to pay the $39.99?
Lastly, @Hal 9000's point that he "...didn't think that the Product Key would work with both versions" is well noted. I find that a bit curious as well.