When I say that it won't show up in the tiny Preview window in Display Properties, I don't mean the big window that opens up when you press the Preview button, but the tiny uh, well...I don't know what else to call it but what Microsoft calls it in all their code, the Preview Window. The little bitty TV-screen window that took all those weeks to get working.
Another possible point of confusion: I'm not sure if all Microsoft operating systems behave this way, but on all the ones I use, right-clicking the icon and using Install does not actually copy anything to the System directory. It just gives Windows a pointer to the current location of the file. That's why changing the current sceensaver will remove MA from the list until it is actually copied into the proper system drawer.
Regarding the download location: Michael has been keeping a repository of previous versions, but the latest Beta can always be downloaded at
http://www.fish-byte.com/MA3Beta.zip .