Windows 8 is the most significant operating system update Microsoft has launched since Windows 95, and the first one designed to run on such a wide range of devices.
To begin with, just to address the elephant in the room, there are two very distinct parts to Windows 8: The Metro interface, and the Desktop interface. The overall experience of using Windows 8 on a non-touch device is so different if you try to use Metro and Desktop together is so different than Desktop alone that we’re going to break it into two stories. This story here deals with Windows 8 on a standard, non-touch PC, applied to the same use cases as Windows XP, Vista, or 7.
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Also: GNUs trick-or-treat at Windows 8 launch