if (document.images) {       
            img51up = new Image();      
            img51up.src = "img/top_ess1_01.gif"; 
            img52up = new Image();      
            img52up.src = "img/top_ess2_01.gif"; 
            img53up = new Image();      
            img53up.src = "img/top_ess3_01.gif"; 
            img54up = new Image();      
            img54up.src = "img/top_id_01.gif"; 
            img55up = new Image();      
            img55up.src = "img/top_catalog_01.gif"; 
            img56up = new Image();
            img56up.src = "img/top_shopping_01.gif"; 
            img57up = new Image();
            img57up.src = "img/top_tab1_01.gif"; 
            img58up = new Image();
            img58up.src = "img/top_tab2_01.gif"; 
            img59up = new Image();
            img59up.src = "img/top_tab3_01.gif"; 

            img51dn = new Image();      
            img51dn.src = "img/top_ess1_02.gif"; 
            img52dn = new Image();      
            img52dn.src = "img/top_ess2_02.gif"; 
            img53dn = new Image();      
            img53dn.src = "img/top_ess3_02.gif"; 
            img54dn = new Image();      
            img54dn.src = "img/top_id_02.gif"; 
            img55dn = new Image();      
            img55dn.src = "img/top_catalog_02.gif"; 
            img56dn = new Image();
            img56dn.src = "img/top_shopping_02.gif"; 
            img57dn = new Image();
            img57dn.src = "img/top_tab1_02.gif"; 
            img58dn = new Image();
            img58dn.src = "img/top_tab2_02.gif"; 
            img59dn = new Image();
            img59dn.src = "img/top_tab3_02.gif"; 
        }



// Function to 'activate' images.
function imgOn(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "dn.src");
        }
}

// Function to 'deactivate' images.
function imgOff(imgName) {
        if (document.images) {
            document[imgName].src = eval(imgName + "up.src");
        }
}

function ess01MouseOver(){
        imgOn('img51');
}

function ess01MouseOut(){
        imgOff('img51');
}

function ess02MouseOver(){
        imgOn('img52');
}

function ess02MouseOut(){
        imgOff('img52');
}

function ess03MouseOver(){
        imgOn('img53');
}

function ess03MouseOut(){
        imgOff('img53');
}

function id01MouseOver(){
        imgOn('img54');
}

function id01MouseOut(){
        imgOff('img54');
}

function catalog01MouseOver(){
        imgOn('img55');
}

function catalog01MouseOut(){
        imgOff('img55');
}

function shop01MouseOver(){
        imgOn('img56');
}

function shop01MouseOut(){
        imgOff('img56');
}

function menu01MouseOver(){
        imgOn('img57');
}

function menu01MouseOut(){
        imgOff('img57');
}

function menu02MouseOver(){
        imgOn('img58');
}

function menu02MouseOut(){
        imgOff('img58');
}

function menu03MouseOver(){
        imgOn('img59');
}

function menu03MouseOut(){
        imgOff('img59');
}