Can I use jQuery to set the width and height of a background image?

Can I use jQuery to set the width and height of a background image?

I'm just starting my first jQuery project (tutorial from this months Web Designer) and I've got a background image that I want to spread across the entire background, regardless of browser size.  It's big, so I originally had an onload function.  This works fine in Mozilla and Safari but not in IE. 

My question is, can jQuery set a width and height of 100% and have it work in IE?
  1. <script type="text/javascript">
        function setBackground(){
            var elem = document.createElement("img");
            elem.setAttribute("src", "wall.jpg");
            elem.setAttribute("height", "100%");
            elem.setAttribute("width", "100%");
            document.body.appendChild(elem);
        }
    </script>