addMenuHover = function () {

    var lis = document.getElementById("menu").getElementsByTagName("li");

    for (var i = 0; i < lis.length; i++) {

        lis[i].onmouseover = function () {

            this.className += " hover";
        }

        lis[i].onmouseout = function () {

            this.className = this.className.replace(new RegExp(" hover\\b"), "");

        }
    }

}

if (window.attachEvent)  
{
	window.attachEvent("onload", addMenuHover);
}