header:
<script type="text/javascript">
    function toogle_alf(id){
        $("#parent"+id).slideToggle();
    }
</script>

sidebar.php:
  <tr>

    <td><table width="100%" border="0" cellspacing="0" cellpadding="0">

      <tr>

        <td width="215" height="271" align="left" valign="top" background="<?php bloginfo('template_directory'); ?>/img/fon_left.jpg"><table width="215" border="0" cellspacing="0" cellpadding="0">
        <tr>
            <td width="42"></td>
            <td>
                <?php include (TEMPLATEPATH . '/searchform_bar.php'); ?>
            </td>
            <td width="17">&nbsp;</td>
        </tr>
        <?php
        $cats = get_categories();
        $parents = array(3,4);
        $flag = 0;
        foreach ((array)$cats as $cat) {
            if (($flag == 1) and (!in_array($cat->parent, $parents))){
                $flag = 0;
                echo '<img src="';
                bloginfo('template_directory');
                echo '/img/menu_razd.jpg" width="215" height="3" border="0" /></div>

                </tr>';
            }
            if (in_array($cat->parent, $parents)) {
                echo '<a href="' . get_category_link($cat->cat_ID) . '">' . $cat->cat_name . '</a> ';
            } else {
                echo '<tr>

                        <td width="42"></td>

                        <td width="156" class="menu">
                            <a href="' . get_category_link($cat->cat_ID) . '"';
                            if (in_array($cat->cat_ID, $parents)) echo ' onclick="toogle_alf('.$cat->cat_ID.'); return false;"';
                echo    '>' . $cat->cat_name . '</a>

                        </td>
                        <td width="17">&nbsp;</td>

                      </tr>
                      <tr>

                        <td colspan="3"><img src="';
                        bloginfo('template_directory');
                echo '/img/menu_razd.jpg" width="215" height="3" border="0" /></td>

                      </tr>';
            }
            if (in_array($cat->cat_ID, $parents)){
                echo '<tr><td colspan="3"><div class="alf" id="parent'.$cat->cat_ID.'">';
                $flag = 1;
            }
        }
        if ($flag == 1){
            $flag = 0;
            echo '</div></td></tr>';
        }
        ?>
            

        </table></td>

style.css:
.alf {
    display:none;
    padding:0 17px 0 50px;
}

.alf img {
    margin:0 -17px 0 -50px;
}