function setOpacity(el, opacity) {

    opacity /= 100;

    el.style.opacity = opacity;
    el.style.MozOpacity = opacity;
    el.style.filter = "alpha(opacity=" + (opacity*100) + ")";

}

function addToOnload(func) {
    if(typeof(onload) == 'function') {
        var oldOnload = onload;
        onload = function() {   
            oldOnload();
            func();
        }
    } 
    else
        onload = func; 
}