title: Target Framework does not change in Visual Studio 2010
body: <p>When I change the target framework of any project in Visual Studio 2010 it does not actually change the System assembly references. For example if I target v2.0 and check the properties of System and System.Data I can see that they are still both v4.0. If i change the target to v3.5, System stays at v4.0 but System.Core changes to v3.5. </p>
  
  <p>Because of this I am truly not targeting anything except v4.0.</p>