var Navigation = {
    init:function() {

        if(!document.getElementById || !document.createTextNode) { return; }

        var nodes = document.getElementById('navigationmenu').getElementsByTagName('LI');

        for(i = 0; i < nodes.length; i++) {
            if(nodes[i].className != 'heading') {
                nodes[i].onmouseover = function() {
                    this.className += ' down';
                }
                nodes[i].onmouseout = function() {
                    this.className = this.className.replace(/\s*down/, "");
                }
            }
        }
    }
}
window.onload = Navigation.init;