The Ajax Control Toolkit is now available from NuGet. This makes it super easy to add the latest version of the Ajax Control Toolkit to any Web Forms application. If you haven't used NuGet yet, then you are missing out on a great tool which you can use with Visual Studio to add new features to an application. You can use NuGet with both ASP.NET MVC and ASP.NET Web Forms applications. NuGet is compatible with both Websites and Web Applications and it works with both C# and VB.NET applications.
In windows 7 by default ISAPI & CGI Restrictions are not configured. To enable ISAPI & CGI restrictions, GoTo -> Control Panel -> Programs -> Click on "Windows features on or off -> Expand Internet Information Services - >Expand World Wide Web Services ->Select CGI and ISAPI extensions and Click OK. After enabling, Check in IIS, Open your IIS and the feature will be available. What is ISAPI and CGI restrictions : ISAPI and CGI restrictions are request handlers that allow dynamic content to execute on a server. These restrictions are either CGI files (.exe) or ISAPI extensions (.dll). You can add custom ISAPI or CGI restrictions if the IIS configuration system allows this.