[jQuery] custom animated drop-down menu and IE6

[jQuery] custom animated drop-down menu and IE6


surprise, surprise, IE 6 isn't doing what it should be.
I have a custom animated drop down menu that works great in FF and
IE7, but IE6 doesn't even start to animate anything. Live example can
be found at: <a href="http://client.grcmc.org/wip/rerc/
index.php">http://client.grcmc.org/wip/rerc/index.php</a>
JS:
[code]
$("#nav li:has(ul)").hover(
                function(){
                    var ul = $(this).children("ul");
                    if(ul.is(":animated")){
                        ul.stop()
                         .css('top','100%').css('opacity','1')
                         .slideDown("fast");
                    }
                    else{
                        ul.css("display", "none")
                        ul.slideDown("fast");
                    }
                },
                function(){
                    var ul = $(this).children("ul");
                    if(ul.is(":animated")){
                     ul.stop()
                        .css('top','100%')
                        .animate(
                            {top:100, opacity:'hide'},
                            "slow",
                            "easeOutExpo",
                            function(){
                                ul.css('top','100%')
                                .css('height','auto');
                            }
                        );
                    }
                    else{
                     ul.animate(
                        {top:100, opacity:'hide'},
                        "slow",
                        "easeOutExpo",
                        function(){
                            ul.css('top','100%')
                            .css('height','auto');
                        });
                    }
                }
            );
[/code]
HTML
[code]
<ul id="nav">
    <li id="nav_about_us"><a class="top_level" href="about_us.php"
title="About Us">About Us</a>
        <ul>
            <li><a href="staff.php" title="Staff">Staff</a></li>
            <li><a href="board.php" title="Board of Directors">Board of
Directors</a></li>
            <li><a href="speakers_list.php" title="Speakers List">Speakers
List</a></li>
            <li><a href="funding.php" title="Our Funding">Our Funding</a></li>
        </ul>
    </li>
    ...
    <li id="nav_contact_us"><a class="top_level" href="contact.php"
title="Contact Us">Contact Us</a></li>
</ul>
[/code]
Any ideas?