function selectMop() {
    var selected;
    element = document.forms['checkout'].elements['mop'];
    for( i=0; i < element.length; i++) {
        if(element[i].checked) {
            selected = element[i].value;
        }
    }

    if(selected == "Visa" || selected == "MasterCard" || selected == "Discover" || selected == "Amex") {
        showElement('cc_info');
        hideElement('pp_info');
    } else {
        showElement('pp_info');
        hideElement('cc_info');
    }

}