You can check the digital signatures on the installers, but those MD5s look correct based on my own personal Opus Museum:
Note that not all aspects of Opus 9 will work correctly with newer versions of Windows. Explorer Replacement may do some weird things, in particular, as the way it works has had to be changed over the years. (Unless you are still running Windows XP as well; then Opus 9 will be fine, but the OS itself will pose bigger problems. :))