Creating metro style winform in windows 7 using C#
Or just using my framework :)
https://github.com/peters/winforms-modernui
Updated fork: https://github.com/dennismagno/metroframework-modern-ui
You should take a look at https://github.com/viperneo/winforms-modernui it provides Metro style for WinForms applications. It works with NET Framework 2.0 and above.
The strict Metro UI apps are Windows 8 only, and they require WinRT.
But if you want to simulate the Metro style in Windows 7 and Windows Forms, you can use third party controls (or develop your own), such as the Telerik ones,
http://www.telerik.com/products/winforms.aspx