Code:
<BODY>

<CENTER>
<SCRIPT LANGUAGE="JavaScript">

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin
var screen_width = null;
var screen_height = null;
var resolution = null;
if (navigator.javaEnabled()) {
var toolkit = java.awt.Toolkit.getDefaultToolkit();
var screen_size = toolkit.getScreenSize();
screen_width = screen_size.width;
screen_height = screen_size.height;
resolution = toolkit.getScreenResolution();
}
// End -->
</SCRIPT>

<SCRIPT LANGUAGE="JavaScript">
<!-- Begin
if ((screen_width != null)
&& (screen_height != null)
&& (resolution != null)) {
document.write('<center><h1>Monitor Details:</h1><br><hr><br>');
document.write('Screen Width:  '+screen_width+'<BR>');
document.write('Screen Height:  '+screen_height+'<BR>');
document.write('Screen Resolution: '+resolution+'<BR>');
document.write('</center>');
}
else {
document.write('<center><P>');
document.write('I am sorry but we could not determine<P>');
document.write('the details of this screen.  You might<P>');
document.write('not have Java enabled in this browser.<P>');
document.write('</center>');
}
// End -->
</SCRIPT>
</CENTER>