function valButton(btn) {
  var cnt = -1;
  for (var i=btn.length-1; i > -1; i--) {
    if (btn[i].checked) {
      cnt = i; i = -1;
    }
  }
  if (cnt > -1) return btn[cnt].value;
    else return null;
  }

function upd_poll(form) {
  var btn = valButton(form.votes);
  if (btn == null) {
    alert('Wel graag een antwoord kiezen!');
  }
  else {
    var url = 'poll_update.php';
    var params = 'vote='+btn+'';
    new Ajax.Request
    (
      url,
      {
        method: 'get',
        parameters: params,
        onComplete: upd_div
      }
    );
  }
}

function upd_div(request) {
  $('uvxpollcontent').innerHTML = request.responseText;
}