if(navigator.appName == "Microsoft Internet Explorer") {
     http = new ActiveXObject("Microsoft.XMLHTTP"); } 
else {
     http = new XMLHttpRequest(); }

function selCountry() {

     var country = document.getElementById('country').value;
     if(country!=0) {
          http.open('get', 'ajax.asp?t=country&id=' + country);
          http.onreadystatechange = function() {
               document.getElementById('cities').innerHTML = "Loading cities...";
               if (http.readyState == 4) {
                    document.getElementById('cities').innerHTML = http.responseText; }
          };
          http.send(null);
     };
}