As you probably already know, a screensaver is a moving pattern that helps you protect your monitor’s screen from phosphor burn-in casued due to static image or text on screen for long time.
On Windows 7 and Vista, you can configure the time after the screensaver kicks in if the computer is idle. The default timeout is 5 minutes.
To change the screensaver timeout value, right click anywhere on your desktop and select Personalize from the menu. In the Personalize window, click on Screen Saver. Now change the value in the wait field and click OK.
The value in the wait field is the screensaver timeout time. If the computer is idle for this amount of time, then the screensaver is displayed.