function changecontent(url) {
	var req=false;
	if(window.XMLHttpRequest) {
		try { req = new XMLHttpRequest(); }
			catch(e) { req = false; }
	} else if(window.ActiveXObject) {
		try { req = new ActiveXObject("Msxml2.XMLHTTP"); }
			catch(e) { try { req = new ActiveXObject("Microsoft.XMLHTTP"); }
					catch(e) { req = false; } }
	}
	if(!req) return true;
	req.onreadystatechange = function() {
		if (req.readyState == 4) {
			myXML = req.responseText;
			document.getElementById("center").innerHTML=myXML;
//			alert(myXML);
		}
	}
	req.open('GET',url+"&u=1",true);
	req.send(null);
	return false;
}