Microsoft has made available for download the first version of a new set of programming libraries designed to let Windows developers more easily use the so-called Ajax programming style to create highly interactive Web pages.

The company's ASP.Net Ajax 1.0, formerly code named Atlas, was formally made available on Tuesday, Microsoft said. The toolkit is available for download free of charge from Microsoft's Web site.

Developers can use ASP.Net Ajax 1.0 to integrate script libraries with the ASP.Net 2.0 server-based development framework, according to Microsoft. ASP.Net Ajax 1.0 will run on a range of Microsoft operating systems, including Windows 2000, Windows Server 2003, Windows XP, and Windows Vista. It can be used in concert with Visual Studio 2005, Microsoft's primary development environment.

Ajax programming, short for Asynchronous JavaScript and XML, is catching on among Web developers because of its ability to deliver data such as airline fares or local temperatures over the Web almost instantaneously -- without forcing users to reload entire Web pages. "Implemented properly, it makes for a very compelling consumer experience on the Web," says technology analyst Rob Enderle, of the Enderle Group.

Microsoft's challenge now will be to convince Web developers that its Ajax framework is superior to, or at least no worse than, any of the myriad solutions already available from third-party sources -- including the Dojo Foundation and Script.aculo.us -- and more easily integrated with Microsoft client and server products.

To help spur adoption, Microsoft is releasing the source code for ASP.Net Ajax 1.0, according to a blog post by Microsoft program manager Scott Guthrie.

"In addition to shipping the source code for the ASP.Net Ajax Control Toolkit controls, we are also releasing all of the source code for the fully supported ASP.Net Ajax 1.0 release," wrote Guthrie.

Microsoft is also offering fee-based telephone support for ASP.Net Ajax 1.0 users.