Keyboard shortcuts save a lot of time when you have to use the same process again and again. Some of the uncommon keyboard shortcuts in Windows XP and Vista are using shortcuts to minimize and maximize a window.
So here are the keyboard shortcuts for minimizing and maximizing a Window:
To minimize all the windows you can use the keyboard shortcut Windows Key + M or you can also use show desktop (Windows Key + D). I prefer the shortcut for show desktop as you can press it again to show the last active window.
To minimize only the active window, press alt + spacebar and then press N.
Sometimes when you open an application and if it opens by covering only half of the total window size and if you would like to maximize it, you can use the shortcut keys alt + spacebar and then X.
To close an active window, press alt + Spacebar and then C
Other highly used keyboard shortcut would be to lock the computer. Use Windows Key + L to lock the computer. You can also set up a desktop shortcut to lock the computer.
Other related topics that you may want to read:
How to create custom keyboard shortcut to open any application?
How to create custom desktop shortcut?