bannertext = '<iframe border="0" width="' 
    + banner_width + '" height="' + banner_height  
    + '" frameborder="0"  scrolling="no" src="http://banners.brainstorm.name/placement.php?id=' + banner_place + '" ></iframe>';
document.getElementById("bannerrotator-aza-" + banner_place).innerHTML = bannertext;