function getit() {
    var file = $("#changing_top_banner").children('img').attr('src');
    $.post('randBanner.php', {file: file}, function(data){
        $("#changing_top_banner").attr('href',data.url);
        $("#changing_top_banner").attr('title',data.title);
        $("#changing_top_banner").children('img').attr('src','resources/banners/'+data.file);
        $("#changing_top_banner").children('img').attr('alt',data.title);
    }, 'json');
}

$(document).ready(function() {
    setInterval('getit()', 5000);
});