function checkUser(userName)
{
	if(idUser=="") idUser = 0;
	var url = "http://www.kuota.it/kuotaworld/lib/checkValidUser.php?username=" + userName;
	var req = new XMLHttpRequest();  
	req.open("GET", url += (url.match(/\?/) == null ? "?" : "&") + (new Date()).getTime(), true); 
	req.send(null);
}

/*function checkUser(userName)
{
	if(idUser=="") idUser = 0;
	var url = "http://www.kuota.it/kuotaworld/lib/checkValidUser.php?username=" + userName;
	var req = new XMLHttpRequest();  
	req.open("GET", url += (url.match(/\?/) == null ? "?" : "&") + (new Date()).getTime(), true);
	req.onreadystatechange = function (aEvt) {  
		if (req.readyState == 4) {  
			 if(req.status == 200)  
				dump(req.responseText);  
			 else  
				dump("Error loading page\n");  
		}  
	};  
	req.send(null);
}*/