Puoi fare cosi ma esistono altri metodi

Metodo 1 :

File test927a.php
codice:
<? 
if (isset($_POST['availHeight'])) {
 $availHeight = $_POST['availHeight'];
 $availWidth  = $_POST['availWidth'];
 $location = "test927b.php?availHeight=$availHeight&availWidth=$availWidth";
 header("Location: $location ");
 exit; 
} // if (isset($_POST['availHeight']))

?>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>
<head>
<title>Untitled</title>
</head>
<body>
<form id="f1" action="test927a.php" method="post">
 <input type="hidden" name="availHeight">
 <input type="hidden" name="availWidth"> 
</form>
<script language="JavaScript" type="text/javascript">
<!--
document.getElementById('availHeight').value = window.screen.availHeight;
document.getElementById('availWidth').value  = window.screen.availWidth;
document.getElementById('f1').submit();
//-->
</script>

</body>
</html>
File test927b.php
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>
<head>
<title>Untitled</title>
</head>
<body>
Available Height = <? print $_GET['availHeight'] ?>

Available Width  = <? print $_GET['availWidth'] ?>


</body>
</html>