function slideSwitch() {
    var $active = $('#slideShowImageCollection img.active');

    if ($active.length == 0) $active = $('#slideShowImageCollection img:last');

    // use this to pull the images in the order they appear in the markup
    var $next = $active.next().length ? $active.next()
                    : $('#slideShowImageCollection img:first');

    // uncomment the 3 lines below to pull the images in random order

    var $sibs = $active.siblings();
    var rndNum = Math.floor(Math.random() * $sibs.length);
    var $next = $($sibs[rndNum]);

    $active.addClass('last-active');

    $next.css({ opacity: 0.0 })
                    .addClass('active')
                    .animate({ opacity: 1.0 }, 1000, function() {
                        $active.removeClass('active last-active');
                    });
}

$(document).ready(function() {
    $("ul#mainNav li:last").addClass("lastNav")
    setInterval("slideSwitch()", 5000);
});