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.");
}