"updrading" VB6 to .NET is a misnomer. All you get is VB6 code in .NET; generally you can get much better results with a refactor/re-architecture - using a different class model, for example. Perhaps designing to be unit-testable, for example. Or using IoC.
If you just want the code to work (and you're confident you can test it), then fine.
Personally, I would seriously consider a more manual port. And I have a lot of legacy VB6 code, so I know the pain involved.
Every time we've faced this, we've simply re-written it in C# - as an approach, it has proven itself many times over.
Actually - I recommend Brownfield Application Deveopment (Manning) - it may give some valuable insights on things to have in place before you start.
