function set_xmlhttp() {
	try {
		xmlhttp = new XMLHttpRequest();
	} catch (erro) {
		try {
			xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (erro) {
			try {
				xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
			} catch (erro) {
				xmlhttp = false;
			}
		}
	}
}