(a) You want to reduce the long waits for users stemming from the round trips between client and server when passing large quantities of data;
(b) You want to implement a rich UI.
With AJAX, in your client scripts you make asynchronous calls to Web services using XML (XMLHTTP) data transfer. An example of an AJAX-style application is the Microsoft Virtual Earth Site: www.virtualearth.com
[See the blog by invited guest expert Yong Tao about AJAX:
However, AJAX has it complexities and the reality is that you want to stay with what you know - your investment in Microsoft technologies. In addition, why not plan for a package of technologies that are the next generation above AJAX with more power and less complexity? Microsoft has the answer in Atlas which extends AJAX.
As Managers, you are telling us that you are tight for time and you want a one-stop accessible source that provides a good road-map of the technologies that you must be considering. So here's the answer--a link that defines AJAX and Atlas and then provides examples to get you started:
The general portal for Atlas is:
ASP.NET Atlas Overview
Walkthrough: Creating a Basic ASP.NET "Atlas" Web Application
Walkthrough: Creating a Declarative Web Application with ASP.NET "Atlas"
Walkthrough: Creating an Auto-completion Text Box with ASP.NET
Walkthrough: Using ASP.NET "Atlas" Auto-completion with a Server Control
Walkthrough: Creating an "Atlas" Web Application with Data-binding and Templates