Microsoft recommends using Visual Studio 2008 for integrating VSTA v 2. However, if you choose to use Visual Studio 2005 the following will need to be addressed.
1) The framework
VSTA v 2 uses the 3.5 framework. It is very important that references, like System.AddIn, point to the 3.5 versions and not the 2.0 versions. The .Net 3.5 ...