Unit testing uses NUnit in Visual Studio 2010

Have you ever used NUnit in Visual Studio 2010?
If you used it once times, I thought you shall be realized the problem at here. NUnit can't run on .NET 4.0. So how can I run it when I writes Unit Testing? There is have a little trick for running it well. You only added some line of XML in configuration file of NUnit. And this is my work:

Finding the tag and adding the configuration tag is . And the result is

   
   ...

Hope it is useful trick for you!