Muhammed Zakir and yeponlyone, thanks a million for your collective advice. I sincerely appreciate your time. Sorry that a nigh passed before I was able to thank you both.
Yea, it's a 64-bit machine and I practice safe-hex. I don't collect malware. But to be reasonable, everyone is vulnerable. That's why we have programs like GPG4USB and gpg4win, not to mention great films like CITIZENFOUR. I just want to get rid of the old copy of Bitcoin-Qt (which I assumed the overwrite would take care of). I have a subtle paranoia that I'll delete some critical file that Bitcoin Core - Wallet v0.10.0 is borrowing ad lib. Why else is Bitcoin-Qt (circa 2011) still there? Are they both referencing %AppData%\Bitcoin\wallet.dat for the most critical information and would I paralyze Bitcoin Core - Wallet by uninstalling Bitcoin-Qt?
Thoughts . . .
Yes, the important files are in %APPDATA% subdirectories. The "c:\pro...\bitcoin*" folders "only" contain the executable part of bitcoin core/qt. I think the files are still there because with the renaming from bitcoin-qt to bitcoin-core they also changed the name of the folder, but the setup is doing no sort of "cleanup" of files from old versions.