TRWTF is the "install routine" (if you can call it that). Somehow, a hard coded directory path does not seem like a robust way to detect the edition of Windows. Ditto for assuming C: drive in the VBS.
Having been on a desktop software project that delayed x64 support for a long time, I can tell you that management hates to spend cycles on this kind of thing. So I'm not surprised it was a rush job, but even so there is no excuse for not pinging the registry to get the Windows edition and Program Files path.