function createRequest(){
        if(typeof XMLHttpRequest!="undefined")        {
                return new XMLHttpRequest();
        }else if(typeof ActiveXObject!="undefined"){
                var xmlHttp_ver  = false;
                var xmlHttp_vers = ["MSXML2.XmlHttp.5.0","MSXML2.XmlHttp.4.0","MSXML2.XmlHttp.3.0","MSXML2.XmlHttp","Microsoft.XmlHttp"];
                if(!xmlHttp_ver){
                        for(var i=0;i<xmlHttp_vers.length;i++){
                                try{
                                        new ActiveXObject(xmlHttp_vers[i]);
                                        xmlHttp_ver = xmlHttp_vers[i];
                                        break;
                                }catch(oError){;}
                        }
                }
                if(xmlHttp_ver){
                        return new ActiveXObject(xmlHttp_ver);
                }else{
                        throw new Error("Could not create XML HTTP Request.");
                }
        }else{
                throw new Error("Your browser doesn't support an XML HTTP Request.");
        }
}

var xmlHttp;