Right click, select Properties, and then select Screensaver tab. Make sure that your screensaver is selected and that the delay time is set. Then click Apply. To shut off the display, click the "Power..." button on the Screensaver tab. You can then select the timeouts for monitor, hard disks, standby, and hibernation. I'm on a desktop, but on a laptop you may even get options to tell the PC to hibernate when the battery hits a certain percentage.