Microsoft has just released Visual Studio 2005 Express for free (free to download for the next year).
Visual Studio includes applications such as Visual Basic and Visual C# (C "Sharp"), which are used to create Windows applications.
http://msdn.microsoft.com/vstudio/express/
A Microsoft program manager put things a bit more clear than what the VS Express site states:
"Until November 7, 2006, we are promotionally discounting the downloadable versions of Express to free. This doesn't mean that the product turns off after a year, but rather that as long as you download the product before November 7, 2006, you can get it for free and you can use it forever."