Creation of an Accordion menu: jQuery, CSS, Drupal, PHP

Hi, I would enable the Accordion menu functionality in my website (Drupal 6.24). In particular I would have Accordion menu on this page: [login to view URL] (and also in the Italian version) The menu on the left is composed by Categories of products. I want have this scenario: when I click on a category, it will be open the sub-categories (without refreshing the page), but if there is no sub-catgories, it is necessary to open the correct view. Example 1: clicking on "Hydraulic pipes", I want to see the "High pressure" and "Low pressure", then clicking on "High pressure" I want to see the specified sub-categories. (without refreshing the page) Example 2: clicking on "Flange SAE" (that has not sub-categories) it is necessary to open the correspond view ([login to view URL]) Requirements: * I want mantein the currently graphic aspects (CSS) * I want have a modification that has to be maintained in the time (NO problem with updating of the Drupal version) * I want complete the job in 1/2 days, no more