Microsoft Visual Studio Alternative

Microsoft visual studio is a development environment by Microsoft for the development of different languages and platforms including Windows, Mobile, Win CE, silverlight etc.
It has a great interface with extensive features, intellisense and easy integration with various softwares.

http://msdn.microsoft.com/vstudio
http://en.wikipedia.org/wiki/Microsoft_Visual_Studio

Here are few alternatives for this...

Visual Web Developer Express: A free version of visual studio for windows platform that just supports the development of web applications for .net framework.
http://www.microsoft.com/express/web/

Visual C# Express Edition A free version of visual studio for windows platform that just supports the development of Winform C# applications for .net framework.
http://www.microsoft.com/express/windows/

SharpDevelop A free open source IDE for windows platform for the development of C# and VB.net applications for .net framework.
http://www.icsharpcode.net/opensource/sd/

http://en.wikipedia.org/wiki/SharpDevelop

MonoDevelop IDE for windows,mac and linux platform for the development of C#, Java, Boo, Nemerle,C, C++, VB.net and Python.

http://monodevelop.com/

http://en.wikipedia.org/wiki/MonoDevelop