navHover = function() {
    var lis = document.getElementById("mainmenu").getElementsByTagName("LI");
    for (var i=0; i<lis.length; i++) {
        lis[i].onmouseover=function() {
            this.className+=" iehover";
        }

        lis[i].onmouseout=function() {
            this.className=this.className.replace(new RegExp(" iehover\\b"), "");
        }
    }

    lis = document.getElementById("mainmenu").getElementsByTagName("UL");
    for (var i=0; i<lis.length; i++) {
        lis[i].onmouseover=function() {
            this.className+=" iehover";
        }

        lis[i].onmouseout=function() {
            this.className=this.className.replace(new RegExp(" iehover\\b"), "");
        }
    }
}

if (window.attachEvent) window.attachEvent("onload", navHover);