function load_nav_images() {
    if (document.images) {
        pic1=new Image(100,100);
        pic1.src='images/buttons/tab_home.gif';
        pic1.src='images/buttons/tab_home_gray.gif';
        pic1.src='images/buttons/tab_purchase.gif';
        pic1.src='images/buttons/tab_purchase_gray.gif';
        pic1.src='images/buttons/tab_myaccount.gif';
        pic1.src='images/buttons/tab_myaccount_gray.gif';
        pic1.src='images/buttons/tab_merchants.gif';
        pic1.src='images/buttons/tab_merchants_gray.gif';
        pic1.src='images/buttons/tab_aboutus.gif';
        pic1.src='images/buttons/tab_aboutus_gray.gif';
    }
}