One common misconception regarding .NET development is the belief that programmers must purchase a copy of Visual Studio in order to build their C# applications. The truth of the matter is that you are able to build any sort of .NET program using the freely downloadable .NET Framework 4.0 Software Development Kit (SDK). This SDK provides you with numerous managed compilers, command-line utilities, sample code, the .NET class libraries, and a complete documentation system.
The .NET Framework 4.0 SDK setup program (dotnetfx40_full_setup.exe) can be obtained from the .NET download web site (http://msdn.microsoft.com/netframework).
Now, be aware that if you are going to be using Visual Studio 2010 ...