function criaXMLHttp() {
	if (typeof XMLHttpRequest != "undefined")
	return new XMLHttpRequest();
	else if (window.ActiveXObject){
	var versoes = ["MSXML2.XMLHttp.5.0",
	"MSXML2.XMLHttp.4.0", "MSXML2.XMLHttp.3.0",
	"MSXML2.XMLHttp", "Microsoft.XMLHttp"
	];
	}
	for (var i = 0; i < versoes.length; i++){
	try{
	return new ActiveXObject(versoes[i]);
	}catch (e) {}
	}
	throw new Error("Seu browser nao suporta AJAX");
	}