title: Visual Studio 2012 w/ Blend - where is System.Windows.Interactivity?
body: <p>I have a brand new install of VS 2012 Premium on Win8 and am trying to open an existing Silverlight project.  The project has a reference to System.Windows.Interactivity.dll which cannot be found.  VS2012 has Blend built in but where is the SDK?  Do I need to download it from somewhere?  Should I install the Blend Ultimate trial that I had on my old VS2010 machine?</p>