//new ajax object
var XML_Http_Request = false;
function createXMLHttpRequest(){
    XML_Http_Request = false;
    
    if(window.XMLHttpRequest){        //for Mozilla
        XML_Http_Request = new XMLHttpRequest();
        if(XML_Http_Request.overrideMimeType){
            XML_Http_Request.overrideMimeType("text/xml");
        }
    }
    else if(window.ActiveXObject){   //for IE
        try{
            XML_Http_Request = new ActiveXObject("Msxml2.XMLHTTP");
        }catch(e){
            try{
                XML_Http_Request = new ActiveXObject("Microsoft.XMLHTTP");
            }catch(e){}
        }
    }
}