how to get js screenresolution passed to a sessionvariable?

hi, I am trying to get the screenresolution passed from a javascript variable to a PHP variable using sessionvariables, but I can't get it to work, can you help me out to get some code working? I was thinking of something like this, but I'm pretty much a newbie at lots of things, so I'm sure this can be a piece'a cake. Thanks. Simon //put the form value in a sessionvariable session_register('Resolutionx'); //use a hiddenvalue in which js writes the x-resolution <form name="anotherName"> <input type=hidden name="Resolutionx" value="0"> //get the resolution <script language="JavaScript"><!-- x=screen.width; document.anotherName.Resolutionx.value = x; //--></script>