function slideSwitch(slideId, switchSpeed) {
  var tag = 'div';

    var $active = $('#' + slideId + ' '+tag+'.active');

    if ( $active.length == 0 ) $active = $('#' + slideId + ' '+tag+':last');

    var $next =  $active.next(tag).length ? $active.next(tag)
       : $('#' + slideId + ' '+tag+':first');

    /*
    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}, switchSpeed, function() {
            $active.removeClass('active last-active');
        });
}