Read the article at the microsoft site:

Replacing API Calls with .NET Framework Classes
Upgrading to Microsoft .NET
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/replaceapicalls.asp?frame=true
Ken Getz
MCW Technologies
February 2002

Abstract:
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Determine file version information?
Read and write to any location in the registry?
Determine user's special folders, such as the Microsoft Windows® Favorites, or Personal folders?
Retrieve a list of all available drives?
Find out the user's login name, or the computer name?
Retrieve a list of all open windows?

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The .NET common language runtime is meant to be platform non-specific. Whenever you use a Windows API call, you're tying your code to the specific platform
Calling the Windows API (or any unmanaged code in Dlls) from .NET isn't as simple as it was in Visual Basic 6.0.
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