To change the logon screen saver, follow the next steps:

1. Open the Registry Editor click on the Start button on your taskbar, then click on Run and type "regedit" and click on OK to start the regedit utility.
    
2. Expand HKEY_USERS\DEFAULT\Control Panel\Desktop (see picture 1).
   
   

   Picture 1

3. In the details pane (right-side), double-click the "scrnsave.exe" string value item.
    
4. In Value data , type the path and name of the screen saver, and then click OK .
    
5. The modifications you made will be in effect after you reboot your PC.
    

IMPORTANT: Make sure that you specify the path correctly to the screen saver. If the screen saver is located in %SystemRoot%\System32, the explicit path is not required.