function newImage(arg) {
    if (document.images) {
        rslt = new Image();
        rslt.src = arg;
        return rslt;
    }
}
function changeImages() {
    if (document.images && (preloadFlag == true)) {
        for (var i=0; i<changeImages.arguments.length; i+=2) {
            document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
        }
    }
}

var preloadFlag = false;

function preloadImages() {
    if (document.images) {
        corporate_over = newImage("images/button1_OFF.gif");
        apprenticeships_over = newImage("images/button2_OFF.gif");
        localgovt_over = newImage("images/button3_OFF.gif");
        emergencyservices_over = newImage("images/button4_OFF.gif");
        graduateintake_over = newImage("images/button5_OFF.gif");
        majororg_over = newImage("images/button6_OFF.gif");
        preloadFlag = true;
    }
}