if (document.images) {

// ROLLOVER OFF
    img01off = new Image();
    img01off.src = "images/main_nav/nav_02.gif";
    img02off = new Image();
    img02off.src = "images/main_nav/nav_03.gif";
    img03off = new Image();
    img03off.src = "images/main_nav/nav_04.gif";
    img04off = new Image();
    img04off.src = "images/main_nav/nav_05.gif";
    img05off = new Image();
    img05off.src = "images/main_nav/nav_06.gif";
    img06off = new Image();
    img06off.src = "images/main_nav/nav_07.gif";
    img07off = new Image();
    img07off.src = "images/main_nav/nav_08.gif";
    img08off = new Image();
    img08off.src = "images/main_nav/login.gif";
    img09off = new Image();
    img09off.src = "images/main_nav/logout.gif";
        

// ROLLOVER ON
    img01on = new Image();
    img01on.src = "images/main_nav/nav_02_o.gif";
    img02on = new Image();
    img02on.src = "images/main_nav/nav_03_o.gif";
    img03on = new Image();
    img03on.src = "images/main_nav/nav_04_o.gif";
    img04on = new Image();
    img04on.src = "images/main_nav/nav_05_o.gif";
    img05on = new Image();
    img05on.src = "images/main_nav/nav_06_o.gif";
    img06on = new Image();
    img06on.src = "images/main_nav/nav_07_o.gif";
    img07on = new Image();
    img07on.src = "images/main_nav/nav_08_o.gif";    
    img08on = new Image();
    img08on.src = "images/main_nav/login_o.gif";
    img09on = new Image();
    img09on.src = "images/main_nav/logout_o.gif";
}

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

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