A very common language to use with .NET is C#. For me I have found that I can just write Java code, with a few minor changed. However, to get the most out of C# you do need to understand some of it's key differences compared to Java.

Note: some of the following links refer to Visual Studio 2010 and .NET 4, newer versions are available but this is what I am currently working with.

The official C# Language Specification can be found either via http://msdn.microsoft.com/en-us/library/ms228593(v=vs.100).aspx or in your Visual Studio installation, just look in the folder %ProgramFiles(x86)%\Microsoft Visual Studio 10.0\VC#\Specifications\1033

Getting Started with Visual C# http://msdn.microsoft.com/en-us/library/a72418yk(v=vs.100).aspx

C# Reference http://msdn.microsoft.com/en-us/library/618ayhy6(v=vs.100).aspx

Classes and Structs (C# Programming Guide) http://msdn.microsoft.com/en-us/library/ms173109(v=vs.100).aspx - this is where you can find out about Partial Classes....

It is worth spending some time reading C# Optimization Secrets, not just when you want speed but in general.