Some computer users experience problems with glare from the screen. Dark Screen sits over all windows and provides a means of dimming the output between 20 and 90%. Dark Screen is multi monitor aware, and can be used on the main monitor only or all monitors. Everything is controlled from the icon in the Notification area of the Taskbar (where the clock sits). Clicking this icon will open the menu which allows the selection of Multi Monitor Support, and the percentage of dimming of the screen.
As usual it's free and available from http://www.fxc.btinternet.co.uk