function cria() {
	try{
		xmlHttp = new XMLHttpRequest();
	}catch(ee){
		try{
			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
		}catch(e){
			try{
				xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
			}catch(E){
				xmlHttp = false;
			}
		}
	}
	return xmlHttp;
}