xcopy /y "$(ProjectDir)$(TargetFileName).config" "$(TargetDir)"
To enable debugging via the F5 key, I'll use the following settings in Project Properties -> Configuration Properties -> Debugging:
Debug Mode: Program
Start Application: C:\Program Files\NUnit 2.2.8\bin\nunit-gui.exe
Command Line Arguments: CDMA.Business.Test.dll
If you then set your unit test project as the start up project you can just press the F5 key and Visual Studio will automagically build the project, copy the configuration file, run the nunit-gui executable and attach the debugger to it. To skip the last step, just press CTRL-F5 instead.