I get this question a lot, and I explain many of the same things that Paul goes through in this post, so I'd love it if more people would read this material:

The "native" .NET language?
In the comments on my post on language choice, Patrick asked “isn't C# the language that's most 'native' to the .NET environment?” Christopher then follows up with a related question as to whether developers should use functions in the System namespace instead of ones in the Microsoft.VisualBasic namespace because the former might be faster. We see these kinds of questions fairly often, so it's worth discussing them a little bit.
Some related material on MSDN: