You could use menu writer in Design Extender to create the basic menu structure of the categories and a second level popup.
after the menu is created, edit the menu.php file to add the images and other content to the second level popups.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.