Ok, I have found a way around this, that I really appreciate. It's not good to use this kind of method too often as it really isn't recommended for SEO.
I use it to hide or display certain graphic elements depending on screen resolution. I tend to like a centered website wich isn't too wide, so on both sides of the website, I like to add logos + other info, that isn't vital, but that kind of stops the screen from looking too empty. Here is an example : http://www.netjuggler.net/index.php (note you will only see the difference in 1280 +. It works on a resize + reload of page as the javascript is based on page width.
<html>
<head>
</head>
<body>
<div id="para">Some text here</p>
<script type="text/javascript">
if(document.width<1280)
{
elem = document.getElementById("para").style.display = 'none';
}
</script>
</body>
</html>
Note it is important that the javascript is placed right at the bottom of the page...
PS : I'm still looking for a way of changing template depending on screen resolution to try and optimize the website display depending on resolution used.