function slideSwitch(switchSpeed) {
    var $active = $('.slideshow div.active');

    if ($active.length == 0) $active = $('.slideshow div:last');

    var $next = $active.next('div').length ? $active.next('div')
       : $('.slideshow div:first');

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

$(function() {
    setInterval ( "slideSwitch(3000)", 7000 );    
});