Microsoft gained their success long time ago with their OS which offers a better GUI.
they got the trend that time and established a strong foundation.
besides, they are kept on improving their products with various version of windows.
however, Windows is not open source and this is why most of the people dislike.
therefore, they are facing the competition from the Open OS such as LInux recently.
anyway, there are a long way to go for the battle between OOS and OS.if they still want to keep their advantages or succes, they must lead the market with outstanding features in their products.