function FillBilling(f) {
  if(f.billingtoo.checked == true) {
    f.shipping_firstname.value = f.account_firstname.value;
    f.shipping_lastname.value = f.account_lastname.value;
    f.shipping_address.value = f.account_address.value;
    f.shipping_address_two.value = f.account_address_two.value;
    f.shipping_city.value = f.account_city.value;
    f.shipping_state.value = f.account_state.value;
    f.shipping_zip.value = f.account_zip.value;
    f.shipping_phone.value = f.account_phone.value;

    /* If more fields are used, just expand the parameters
       above to include the additional fields. */
  }
}