var agt=navigator.userAgent.toLowerCase(); 
var is_major = parseInt(navigator.appVersion); 
var is_minor = parseFloat(navigator.appVersion); 
var is_ie   = (agt.indexOf("msie") != -1); 
var is_ie3  = (is_ie && (is_major < 4)); 
var is_ie4  = (is_ie && (is_major == 4) && (agt.indexOf("msie 5.0")==-1) ); 
var is_ie4up  = (is_ie  && (is_major >= 4));       
var is_ie5  = (is_ie && (is_major == 4) && (agt.indexOf("msie 5.0")!=-1) ); 
var is_ie5up  = (is_ie  && !is_ie3 && !is_ie4); 

function ToggleMenu() {
    ShowMenuImage = new Image;
    HideMenuImage = new Image;
    ShowMenuImage.src = "/images/show_menu.gif";
    HideMenuImage.src = "/images/hide_menu.gif";

    if (document.all.LeftMenu.style.display=='')
    {
        document.all.LeftMenu.style.display='none';
        document.images["MenuImage"].src = ShowMenuImage.src; 
    }
    else
    {
        document.all.LeftMenu.style.display='';
        document.images["MenuImage"].src = HideMenuImage.src; 
    }
}