show/hide second level dynamic navigation – how?

Hi there,
I have a static html file containing a vertical nav;

<ul>
 <li>First Level
   <ul>
    <li>Second Level</li>
   </ul>
 </li>
</ul>

That kinda thing, live demo here (albeit un-styled);

http://web.mydns.net.nz/one-to-one.co.nz/wp-content/themes/121/navigation.html

Anyway, I have used this code (below) to dynamically generate the nav now – rather than hard code it;

<div id="sidebar1">
  <?php if(wp_list_pages("title_li=&child_of=$parent&echo=0" )): ?>
  <div id="submenu">
    <ul>
      <?php wp_list_pages("title_li=&child_of=$parent" ); ?>
    </ul>
  </div>
  <?php endif; ?>
</div>

Live demo here (styled): http://web.mydns.net.nz/one-to-one.co.nz/

But now, how do I enable the show/hide rollover effect for the second level navigation (seeing as it’s dynamically generated)?

Thanks in advance…
No idea