function setAjax () {
  try {
    xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
  } catch (e) {
    try {
      xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    } catch (E) {
      xmlhttp = false;
    }
  }
  if (!xmlhttp && typeof XMLHttpRequest!='undefined') {
  	try {
  		xmlhttp = new XMLHttpRequest();
  	} catch (e) {
  		xmlhttp=false;
  	}
  }
  if (!xmlhttp && window.createRequest) {
  	try {
  		xmlhttp = window.createRequest();
  	} catch (e) {
  		xmlhttp=false;
  	}
  }
}