In VS 2003 most cases of using Interop to allow you to use COM work fine. We were trying to re-write a custom catalog editor for Commerce Server 2000 from VB6 to VB.net 2003. Their seems to be a problem regarding the compartmentalizing of the catalog.dll suppied with Commerce Server 2000 that will not work with creating a wrapper and using in VB.net. Do not try, you are wasting your time. This has been verified with Microsoft Technical services.