As <em>talkswithnumbers</em> mentioned above, my C# wrapper takes the trouble out of having to know COM Interop to write GDS plugins. My library code will do the dirty job of talking to GDS and you can focus your energies on your application code, in C# or VB.Net, or any other .Net language.

The license is open enough (LGPL), the source code is available, :) you should give it a try. If you have any questions, I'll be glad to help. Why reinvent the wheel?