function ajappendcart(aProdID){

  var url = '/ajax.php';

  new Ajax.Request(url, {
    method: 'get',
    parameters: 'act=appcrt&pid=' + aProdID,
    onSuccess: ajappendcartonSuccess } );
}

function ajappendcartonSuccess(transport) {
  $('header_cart').innerHTML = transport.responseText;
}