You could also do this:
Visual Studio Configuration Manager: Add two entries, QA and DEV.
Copy Web.Config into four new files, Web.Config.QA, Web.Config.DEV,
Web.Config.release, and Web.Config.debug and make the appropriate changes to
target the desired system.
Add a Build Event Pre-Build event command line:
"$(ProjectDir)CopyConfig.bat" "$(ProjectDir)web.config.$(ConfigurationName)"
"$(ProjectDir)web.config"
Create CopyConfig.bat with the following and add to project root.
@echo off
echo Comparing two files: %1 with %2
if not exist %1 goto File1NotFound
if not exist %2 goto File2NotFound
fc %1 %2
if %ERRORLEVEL%==0 GOTO NoCopy
echo Files are not the same. Copying %1 over %2
copy %1 %2 /y & goto END
:NoCopy
echo Files are the same. Did nothing
goto END
:File1NotFound
echo %1 not found.
goto END
:File2NotFound
copy %1 %2 /y
goto END
:END
echo Done.
Regards,
Brian K. Williams