Will Nikon's Picture Project free software work on my Windows 10? I would be downloading pictures from my Nikon D80 camera.
No, the software will not work on the Windows 10 operating systems because there would be no place to download then. There is only an updated to the application that Nikon released, but that's it.
According to the official website, the software has been discontinued. You will need ViewNX application in order to transfer files: https://support.nikonusa.com/app/answers/detail/a_id/61/~/current-versions-of-nikon-software