wp_nav_menu adding code to each ?

Hey all,

Been looking at this for a while now, and have hit a brick wall.

I have a static site layout created, and the navigation uses drop downs, and once each link is rolled over it has a jquery rollover effect that displays an image on each navigation element in a particular drop down.

Similar to this effect – http://cssglobe.com/lab/tooltip/03/

An example of the code form the static site is below:

<li><a href="applications-snow-plough.html" class="screenshot" rel="site_images/pop/snowplough-pop.jpg">Snow plough</a></li>

I am wondering how I would be able to make this effect apply to a wordpress version of the site I am working on.

I am using the ‘menus’ feature in the wordpress admin area, and am calling the navigation menu in my theme as follows.

<div id="navigation"><?php wp_nav_menu( array( 'theme_location' => 'primary' ) ); ?></div> <!-- #navigation -->

I would like to be able to add the following to each navigation item (in a particular dropdown, not every link)

class="screenshot" rel="site_images/pop/snowplough-pop.jpg"

the next issue I have is trying to figure out how to call a featured image from each page that the nav points, and have appear as the pop up jquery image – I have a funny feeling this is going to be a nightmare to solve!