function setCookie(key, val) {
  
  str = key + "=" + escape(val) + "; ";
  str += "expires=Tue, 31-Dec-2010 23:59:59; ";
  document.cookie = str;
  
}

function setPref(){
  
  var elm = document.getElementById("area");
  var selected = elm.options[elm.selectedIndex].value;
  
  setCookie("pref", selected);
  
}