ASP.NET Ajax Introduction

http://msdn.microsoft.com/msdnmag/issues/07/02/cuttingedge/default.aspx

"Perspectives on ASP.NET AJAX," by Dino Esposito. Discusses ways to use AJAX in ASP.NET, the straight way to ASP.NET AJAX, the UpdatePanel, the Interceptor Pattern, taking control of out of band calls, page methods vs. web services methods and Dino's way to ASP.NET AJAX.

An Introduction to AJAX and Atlas with ASP.NET 2.0

http://aspnet.4guysfromrolla.com/articles/062106-1.aspx

"An Introduction to AJAX and Atlas with ASP.NET 2.0," by Erich Peterson. Discusses what AJAX is, the basic concepts of AJAX and the Microsoft Atlas framework, a basic Altas example, the UpdatePanel, the mode attribute and building an Atlas-enabled GridView.

Introduction to Drag And Drop with Atlas

http://aspadvice.com/blogs/garbin/archive/2006/01/17/14730.aspx

"Introduction to Drag And Drop with Atlas," from Atlas Notes. Discusses draggable items and drop targets, the IDragSource interface, the IDropTarget interface, the DragDropManager, creating a draggable item, built-in classes for Drag&Drop, the DragDropList behavior, the DraggableListItem behavior, the DataSourceDropTarget behavior and the FloatingBehavior.

An Introduction to ASP.NET AJAX

http://steveorr.net/articles/aspnetajax.aspx

"Introduction to ASP.NET AJAX," by Steve C. Orr. Discusses what ASP.NET Ajax is, how ASP.NET AJAX works and new server side controls for ASP.NET AJAX that include the Scriptmanager, the ScriptManagerProxy, the UpdatePanel, the UpdateProgress and the Timer.

Introduction to the UpdatePanel Control

http://ajax.asp.net/docs/tutorials/introductionupdatepanel.aspx

"Introduction to the UpdatePanel Control," from ASP.NET AJAX. Discusses adding partial-page update support to a web page using AJAX extensions, the ScriptManager control, the Updatepanel control, how to use the UpdatePanel, understanding the benefits of the UpdatePanel control and refreshing an UpdatePanel control with an external button.