Before reading this tutorial you should be familiar with ASP.NET and C# or VB.NET (examples will be provided in both C# and VB.NET). If you don't already have Visual Studio installed on your computer you can download Visual Web Developer 2005 Express Edition freely from the Microsoft website. To download AJAX Extension go to www.asp.net, click on "AJAX" tab at the top of the page, then click on the "Download" button, and at last click "Download ASP.NET AJAX v1.0" button. Save the file and run the installer.