activateMenu = function (nav) {

    if (document.all && document.getElementById) {
        navRoot = document.getElementById("nav");
        for (i = 0; i < navRoot.childNodes.length; i++) {
            node = navRoot.childNodes[i];
            if (node.nodeName == "LI") {
                node.onmouseover = function () {
                    this.className += " over";
                }
                node.onmouseout = function () {
                    this.className = this.className.replace(" over", "");
                }
            }
        }
    }
}
window.onload = function () {
    /* pass the function the id of the top level UL */

    /* remove one, when only using one menu */
    activateMenu("nav");
}