The version of RadAjax in the picture you referenced is different than the version you typed. Assuming you want the later, it is from the Q2 2007 SP1 release (Release Notes: http://www.telerik.com/versionnotes.aspx?id=837). This is a very old version, though, so I would encourage you to consider upgrading to the newer, more powerful RadAjax for ASP.NET AJAX (which is obviously based on the ASP.NET AJAX framework). If that's not an option, you would probably be best served by downloading the Q1 2009 version of the RadAjax for ASP.NET Classic to ensure you get all the bug fixes possible.
Another tip about telerik rad controls versions -- take a look at the source of the page and you will find some href pointing to Telerik.Web.UI.WebResource.axd - and in its parameters you often (always?) find the actual version used for this page.
A simple way to find - search for 200 (as part of 2007 / 2008 / 2009) and with the most current release you'll find
2009.1.402.35 - or with this forum 2008.2.1001.20.
This helps me a lot with remote client sites - because so I can check what I run there without having direct server access.