function createXMLHTTP(){
	var ajax;
  	try {
   		ajax = new ActiveXObject("Microsoft.XMLHTTP");
	} 
  	catch(e){
		try{
    		ajax = new ActiveXObject("Msxml2.XMLHTTP");
    		alert(ajax);
   		}
   		catch(ex){
    		try {
				ajax = new XMLHttpRequest();
			}
			catch(exc){
      			alert("Esse browser não tem recursos para uso do Ajax");
      			ajax = null;
			}
		}
		return ajax;
	}
    var arrSignatures = [
		"MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0",
        "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP",
        "Microsoft.XMLHTTP"
	];
    for (var i=0; i < arrSignatures.length; i++){
    	try{
     		var oRequest = new ActiveXObject(arrSignatures[i]);
     		return oRequest;
		} 
    	catch (oError){
		}
	}
	throw new Error("MSXML is not installed on your system.");
}