if (document.images) {            // Active Images
    img1on = new Image();      
    img1on.src = "/global/images/bulletin4_s.gif"; 

    img1off = new Image(); 
    img1off.src = "/global/images/bulletin4.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");
        }
}