Right now, MS is pushing for the Windows 8 / VS11 toolset for cutting-edge developers. But for many of us maintaining current systems, its still nice to know what you'd need to get started for their environment. I should point out that in the past, I've used SharpDevelop for my own projects: unfortunately, converting older open-source VS projects seems a hassle in SD.
* Visual Studio 2010 Express (C# / VB.NET / C++)
* Visual Studio 2010 Shell
* Python Tools for Visual Studio
* Microsoft Windows SDK
Edit: it might also help to know where to grab non-Microsoft .NET parts: namely Mono & GTK# stuff to use cross-platform with Windows and Linux.
* Mono & GTK#