Microsoft Windows XP - Save Time By Simultaneously Closing All Open Applications (Win XP)
When you're done working on your computer for the day, you probably close each open application individually. If so, chances are that you've wished you could close all your open applications at the same time. Fortunately, Windows XP includes a hidden technique that allows you to do so.
To begin, hold down the [Ctrl] key and click on each application button on your taskbar. When you do, you'll notice that each button remains selected. Once you've selected all the application buttons on the taskbar, right-click on any one of them and select the Close command (or Close Group if you have open more than one file of each application type) from the shortcut menu. When you do, all your applications close. If you have any application in which an open file hasn't yet been saved, that application prompts you to save the file.