if (document.images) {

// off
    img1off = new Image();
    img1off.src = "img/nav_home1.gif";
    img2off = new Image();
    img2off.src = "img/nav_models1.gif";
    img3off = new Image();
    img3off.src = "img/nav_act1.gif";
    img4off = new Image();
    img4off.src = "img/nav_extras1.gif";
    img5off = new Image();
    img5off.src = "img/nav_fin1.gif";
    img6off = new Image();
    img6off.src = "img/nav_idea1.gif";

    img7off = new Image();
    img7off.src = "img/navside_testdrive1.gif";
    img8off = new Image();
    img8off.src = "img/navside_request1.gif";
    img9off = new Image();
    img9off.src = "img/navside_centre1.gif";
    img10off = new Image();
    img10off.src = "img/navside_contact1.gif";


// on
    img1on = new Image();
    img1on.src = "img/nav_home2.gif";
    img2on = new Image();
    img2on.src = "img/nav_models2.gif";
    img3on = new Image();
    img3on.src = "img/nav_act2.gif";
    img4on = new Image();
    img4on.src = "img/nav_extras2.gif";
    img5on = new Image();
    img5on.src = "img/nav_fin2.gif";
    img6on = new Image();
    img6on.src = "img/nav_idea2.gif";

    img7on = new Image();
    img7on.src = "img/navside_testdrive2.gif";
    img8on = new Image();
    img8on.src = "img/navside_request2.gif";
    img9on = new Image();
    img9on.src = "img/navside_centre2.gif";
    img10on = new Image();
    img10on.src = "img/navside_contact2.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");
        }
}