startList = function() {
    if (document.all && document.getElementById) {
        navRoot = document.getElementById("nav");
        var liTags = navRoot.getElementsByTagName("LI");
        for (var i = 0; i < liTags.length; i++) {
            node = liTags[i];
            node.onmouseover=function() {
                this.className+=" over";
            }
            node.onmouseout=function() {
                this.className=this.className.replace(" over", "");
            }
        }
    };
}

window.onload=startList;