activateMenu = function(nav) {
/* currentStyle restricts the Javascript to IE only */
    if (document.all && document.getElementById(nav).currentStyle) {
        var navroot = document.getElementById(nav);

        /* Get all the list items within the menu */
        var lis = navroot.getElementsByTagName("LI");
        for (i = 0; i < lis.length; i++) {
            
            /* If the LI has another menu level */
            if (lis[i].lastChild.tagName == "UL") {

                /* assign the function to the LI */
                lis[i].onmouseover = function() {

                    /* display the inner menu */
                    this.lastChild.style.display = "block";
                }
                lis[i].onmouseout = function() {
                    this.lastChild.style.display = "none";
                }
            }
        }
    }
}
window.onload= function(){
    /* pass the function the id of the top level UL */
    /* remove one, when only using one menu */
    activateMenu('nav'); 
}