The Lawtech website uses Microsoft Silverlight to animate the menu and header images in a slideshow at the top of the webpage.

Microsoft Silverlight is an application framework for writing and running rich internet applications, with features and purposes similar to those of Adobe Flash. The run-time environment for Silverlight is available as a plug-in for most web browsers. While early versions of Silverlight focused on streaming media, current versions support multimedia, graphics and animation, and give developers support for CLI languages and development tools. Silverlight is also one of the two application development platforms for Windows Phone 7.

If you don't currently have the Microsoft Silverlight plugin installed in your web browser, the page will display a non-animated fixed image and menu.

You can read more about Microsoft Silverlight

You can download Microsoft Silverlight plugin here