This option is already available in Windows - you can manually start the built in Windows Screensavers by going to the System 32 folder in Windows and either search for, or scroll down to each Screensaver file and creating a shortcut on your desktop for each particular .exe file. Just keep in mind that if you manually start the Screensaver from the desktop, any slight mouse movement will turn it off. I am speaking of Win 8.1 but I recall that it is the same for previous versions of Windows. Just remember to turn off any Screensavers in the Control Panel as to not conflict with your manually started SS.