function getXmlHttp(){
 var xmlHttp;
 try
 {
   xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
 } catch (e) {
   try {
     xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
   } catch (E) {
     xmlHttp = false;
   }
 }
 if (!xmlHttp && typeof XMLHttpRequest!='undefined') {
   xmlHttp = new XMLHttpRequest();
 }
 return xmlHttp;
}