AutoCAD addin

Create an addin to work with: - AutoCAD 2004 to 2009. To have a toolbar with various sample buttons and menus on the main AutoCAD menus. - AutoCAD 2010 & 2011 To create a Ribbon Page with various style buttons. Functionality: - To be able to call external DLL (a small sample to be provided) and to integrate with internal AutoCAD API to: 1- Create new document, 2- Insert blocks, 3- check for XREFs for this drawing - The addin must be able to load automatically when AutoCAD starts. TOOLS - Use Visual Studio 2008 or 2010, .NET platform 3.5 - Not to use any 3-rd party DLL's unless we approve them first.