To activate and deactivate the screen saver whenever you want,
goto the following registry key:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
\ScreenSavers

Now add a new string value and name it Mouse Corners. Edit this
new value to -Y-N. Press F5 to refresh the registry. Voila! Now you
can activate your screensaver by simply placing the mouse cursor
at the top right corner of the screen and if you take the mouse to
the bottom left corner of the screen, the screensaver will
deactivate. 




Enjoyyyy................