I had to reformat my computer recently. Does anyone out there still have a copy of the original myst masterpiece installer from before SCUMMVM was added? I prefer the original build when running on my Windows XP build for various reasons. I thankfully still have the originals for Riven, cd and dvd versions.

LOL. ... Windows XP....Hehehe.

I'm curious enough to ask, why are you asking for that version? Are you one of those madmen who'd buy a Macintosh Plus to run Myst?

I'm not sure, but using GOG Galaxy you might be able to download an early release of the game, before ScummVM was added. Unfortunately GOG Galaxy doesn't work on Windows XP, so you have to use another system and then transfer the files on the Windows XP machine.
Another solution might be writing to GOG support and asking them to send you a direct link to download an older installer, if still available.