Joel at StackPop Studios offers a super-hand-holding, step-by-step tutorial on creating multiple versions of the same game in Visual Studio.
Every step gets its own screenshot, and every code sample is fairly straightforward.
Visual Studio's configuration manager apparently delivers some pretty potent ibuprofen to the version-management headache, as Joel explains:
"Taking the time to set this up for your game project files can be a huge savings managing different versions. We found it tremendously helpful in testing and shipping paid and free versions and making sure we got each right."
Read the full (shorter-than-it-looks) guide here.