Here is a good news for developers. Microsoft has released a light weight version of Visual Studio .NET and it is free. These free editions are called "Express Editions".
It is split into several small products and it is FREE for 1 year. If you download them within 1 year from the date of release, you can use them free for ever!
Visual Studio Express Editions
The following express editions of Visual Studio 2005 are avalable for free download from the release date of Visual Studio 2005. (If you download and register the below express editions before November 2006, it is free for ever.)
Visual Basic Express Edition
Visual C++ Express Edition
Visual J# Express Edition
Visual C# Express Edition
Visual Web Developer 2005 Express Edition
There is an SQL Server Express also available, which will be free without the 1 year registration requirement.
You just need to download the most appropriate version for you. If you want to write VB.NET applications, download Visual Basic Express edition. If you want to write ASP.NET applications, download Visual Web Developer 2005 Express Edition.
If you are planning to work on all of the above, it is a good idea to download and install all of them.
You may download the express editions of VS.NET from http://msdn.microsoft.com/vstudio/express/default.aspx