At some point in your .NET programming, you're always going to have to jump outside the safe confines of the Framework Class Library and ask the OS to do some work for you that you can't get anywhere else. Fortunately, the interoperability layers in .NET programming make it relatively easy, provided you understand C programming and Windows idiosyncrasies, both of which are hard to chew if you've never seen them before.
Probably the best advice I can give you is to get the following book: Dan Appleman's Visual Basic Programmer's Guide to the Win32 API. (Yes, the author's name is part of the title. It must make him feel important :P ) While the book is written for Visual Basic 6, it will guide you into the opportunities and Visual Basic types you'll need to translate into Visual Basic .NET. You'll also want to start reading how to do interop at http://msdn.microsoft.com/vstudio/using/understand/interop/default.aspx.
This was first published in September 2003