OK sprinter,
Double-clicking on the blue bar at the top of an open window maximises the window (saves trying to line-up your pointer with the little box in the corner - handy if you have a touch pad rather than a mouse - or if you've had too many beers!!!)
Holding down "Alt" and "F4" together closes the current window in use - when they're all closed it acts like clicking "start" then "turn off computer" (handy if you're in a hurry or too lazy to click all the little X's !!!)