What are some convincing arguments to upgrade from Visual Studio 6?

Question

I have a client who is still using Visual Studio 6 for building production systems. They write multi-threaded systems that use STL and run on mutli-processor machines.

Answer 1

The VS 2008 version of the STL compiles with /clr, so if they're interested in transitioning to the managed world, they don't have to lose all their old code.