var httpReq;

function getScreenSize() { 	
	if (window.XMLHttpRequest) {
		httpReq = new XMLHttpRequest();
	} else if (window.ActiveXObject) {
		httpReq = new ActiveXObject("Microsoft.XMLHTTP");
	}
	
	var screenW = 640, screenH = 480;
	if (parseInt(navigator.appVersion)>3) {
 		screenW = screen.width;
 		screenH = screen.height;
 	}
  
  	var url = "/screenSize.jsp?width=" + screenW + "&height=" + screenH;
  	
   	httpReq.onreadystatechange = setScreenSize;
   	// if httpReq is privatized then use http_request.onreadystatechange = function() { processZipData(httpReq); };
   	httpReq.open("GET", url);
   	httpReq.send(null);
}

function setScreenSize(){
	if (httpReq.readyState == 4) {
    	if (httpReq.status == 200) { // 200=success, 404=not found
    		var data = httpReq.responseText;    		
    	} else {		
    	}
    }
}

getScreenSize();