There’s still a lot of Visual Basic 6 systems running the world and if you’re one of the developers maintaining those systems you may be looking at migration strategies to move to .NET. You don’t have to take on a complete rewrite of your system, there are many ways of interoperating with VB6 from .NET and vice versa.
Check out Rob Windsor on dnrTV where he shows us how to interoperate with VB 6.0 applications and .NET in a variety of ways. He walks through different approaches to architecting these hybrid systems. He also shows how to use the Interop Forms Toolkit to demonstrate a phased migration strategy where you can convert VB 6 forms and controls to .NET pieces at a time.