function preload()
{
    Home = new Image(57,35);
    Home.src = "images/es1_home.png";
    HomeOn = new Image(57,35);
    HomeOn.src = "images/es1_home_on.png";
    Clients = new Image(60,35);
    Clients.src = "images/es1_clients.png";
    ClientsOn = new Image(60,35);
    ClientsOn.src = "images/es1_clients_on.png";
    Contact = new Image(76,35);
    Contact.src = "images/es1_contact.png";
    ContactOn = new Image(76,35);
    ContactOn.src = "images/es1_contact_on.png";
}

function swap(imgDocID,imgObjName)
{
    document[imgDocID].src = eval(imgObjName + ".src");
}

preload();