Tabbed Categories and Posts

I’m trying to create a tabbed area with a list of categories which can be clicked to show the posts in each of them.

I’ve tried everything I can find and the latest attempt is this:

<div id="tabs">
   <ul class="cat-list">
      <?php
      $cat_args = array(
          'orderby' => 'name',
          'order' => 'ASC',
          'child_of' => 0
      );

      $categories = get_categories($cat_args);

      foreach ($categories as $category) {
         echo '<li> <a href="#' . ( $category->cat_ID ) . '" title="' . sprintf(__("View all posts in %s"), $category->name) . '" ' . '>' . $category->name . '</a></li>';
      }
      echo '</ul> ';
      foreach ($categories as $category) {

         echo '<div id="' . ( $category->cat_ID ) . '"><ul class="post-list">';

         $post_args = array(
             'numberposts' => 20,
             'category' => $category->term_id
         );
         echo '<pre>' . print_r($category, 1);
         $posts = get_posts($post_args);

         foreach ($posts as $post) {

            echo '<li><a href="'.the_permalink().'">'.the_title().'</a></li>';
         }
         echo '</ul></div>';
      }
      ?>
</div>

The categories must be listed in a

and closed with the posts for each category being listed in a <div> with the id of the category after

Any ideas?