Update: I forgot to explain some things about charms in the above video, so I recorded the second video http://youtu.be/PMc92O7VbPA, which is just 2 minutes long. I recommend you to see it also. Sorry guys to give you some more pain for just two minutes ;p.
Note: the term "Metro" apps is dropped and are now officially called as "Windows 8" apps.
Microsoft aims its next OS to be touch friendly so that it can be used very easily on tablets. In that direction, Microsoft's design team conceptualized Metro design principles and Metro design language. The Metro design principles and language are used in Windows Phone 7 and later versions. And now Windows 8 follows the same path. The design approach is evolved from the Zune devices' UI. And is quite clean and neat. You can learn more about metro at Mocrosoft's design leads' blog.
Since Windows 8's UI is aimed to simplify touch gestures, it was quite unclear how it will work on traditional desktops with mouse input. However, the OS still remains very easy to use and intuitive to work with mouse with some added mouse-actions to deal with Metro UI. The Windows 7 like desktop environment is still there and is full functional. We can work with it the way we are doing right from Windows 95 days. The only difference is the Start menu which is Metro-ized and Metro apps which runs full screen (no title/status bar) and have live tiles (instead of icons).
People first time using Windows 8 may find it difficult learn these new mouse-actions to deal with Metro. But these mouse movements are quite intuitive and easy. Thus, in this 5 minute video I explained how we can use Windows 8 with mouse to work with Metro and traditional desktop environment together. Hope this helps.
