Image crossfader

$(document).ready(function(){
        $(".dropnavoption").mouseover(function(){
            var oldimg = $('#swapme').css("background-image")
            //alert(oldimg);
            $('#swapmetoo').css('background-image', oldimg);
            $('#swapmetoo').show();
            $('#swapme').hide();
            var image = $(this).attr('rel');
            //alert(image);
            $('#swapme').css("background-image", 'url('+image+')');
            $('#swapme').show();
            $('#swapmetoo').fadeOut('slow');
        });
    });
//This assumes you have to divs set two absolute with same positioning