Not to discourage you, but simply giving the executable a SCR extension isn't going to work. The screen saver needs to accept command line arguments for running the screen saver, previewing, options, etc. The screen saver also needs to check to make sure there isn't a previous instance already running. I made a screen saver and used Visual Basic as a 'front end' to handle options, check for previous instances, put an image into the preview window, and to launch the SCR. It involved using quite a bit of the Windows API.
Looking for the vortex to another Earth