How can I easily have different app.config files for different build configurations in MSBUILD?

There are a few different proposed solutions I have seen suggested, some including recommendations involving 3rd party tools and Visual Studio Transformation Extensions. The following is the simplest method I have found. It involves a violation of the DRY principle (Don't Repeat Yourself) as the app.config files are duplicated (due to the lack of transforms) - but I considered this to be a small sacrifice based on the simplicity of the solution.

Steps:
1) Unload your Project file (csproj) file in Visual Studio and Right click and select "Edit {My Project Name}.csproj" on that same file to edit it.
2) Add a folder for each MSBUILD configuration that you want and put your different App.Config files in those subfolders e.g. \Release\App.config and \Debug\App.Config
2) Find the section in your csproj project file <None Include="App.config" /> and replace it with the following conditional Include statements for each of your MSBUILD configurations:

<None Condition=" '$(Configuration)' == 'Debug' " Include="Debug\App.config" />
<None Condition=" '$(Configuration)' == 'Release' " Include="Release\App.config" />

When you build, it will use either of the application configuration files that you have created and put them in the relevant build configuration output directory.

DDK