Theres a request with this entry from my last blog, and because i can still remember it, im going to post it here. the image stated in the url will be fixed no matter how the page is scrolled down.
<style type="text/css">
<!--
body
{
background-attachment: fixed;
background-image: url;
background-repeat: no-repeat;
background-position: right top;
}
-->
</style>
