To get started creating dynamic web sites with ASP.NET, you will need the following two downloads. Both downloads are free, and both are provided in your choice of language. For more information on whats new in Visual Studio 2008 and ASP.NET 3.5 go to the new features page. For more information on ASP.NET in the .NET Framework 3.5 Service Pack 1 go to the SP1 page
The Microsoft .NET Framework is a component of the Windows operating system. It provides the foundation for next-generation applications, including ASP.NET web applications.
The Microsoft .NET Framework Version 3.5 SP1 can be downloaded from here:
Visual Web Developer 2008 Express Edition is an easy to use and easy to learn program that allows everyone, from the novice to the professional developer, to create ASP.NET web sites.
The 2008 version of Visual Web Developer Express Edition can be downloaded from here:
ASP.NET AJAX is a free framework for quickly creating a new generation of more efficient and interactive Web experiences that work across all the most popular browsers. It is included as part of ASP.NET 3.5 directly or can be installed as an add-on to ASP.NET 2.0.
Get ASP.NET AJAX Components
Get the ASP.NET AJAX Control Toolkit