The ESRI developer addins for Visual Studio .NET appear under the Tools menu after running the RegisterDotNetAddins.bat file. The addins should also be listed in the Addin Manager dialog box, also found under the Tools menu. If the ESRI addins cannot be found, re-register the addins to the specific Visual Studio .NET version. ArcGIS 9.0 supports Visual Studio .NET 2003.
The ArcGIS 9.1 installation will register the addins specifically to Visual Studio .NET 2003.
The addin registration utility registers the addins to the supported version of Visual Studio by default. For example, if the installed version of Visual Studio is unsupported, the addins will not show up in Visual Studio .NET.
An installation of Visual Studio Express may also be the cause.
esriRegDotNetAddIn.exe /all /version:7.1