I have some simple dropdown lists in pairs, like Country/State selection, what I want is: when user selects a country from the country list, the list of the states of that country will be shown in the state dropdown list, and the selection of the country is still preserved in the country list. Most important: there is no postback so the page will not refresh every time when a selection is made. What's the easiest way to implement this? Do I have to use AJAX? I know the new AJAX CascadingDropDown control is perfect for this, but I found I couldn't find the ASP.NET AJAX Control Toolkit for .NET 2.0 in their website, all the current downloads seem to be in framework 3.5? Correct me if I am wrong, thanks for any help.