One reason developers cite for sticking with Visual Basic 6 instead of migrating to the .NET Framework is the presence of existing VB 6 applications. These apps have typically been around for years, with features added and modified at various intervals, and would benefit from a rewrite rather than an upgrade. Besides, an upgrade is hardly the appropriate time to start getting cozy with .NET.
Fortunately, Microsoft recognized this and allows developers to leave these apps in VB 6 and call into the .NET Framework whenever necessary. Doing so provides easy access to the framework's class libraries and may eliminate the need for certain API calls.
In a May 2006 MSDN article, consultant Scott Swigart demonstrates how to call into .NET with an application in VB 6. Doing so requires either Visual Studio 2005 or Visual Basic Express and a code download that is included with the article.