Code
<html>
<head>
<title>Страничка с неподвижным фоном</title>
<style type="text/css">
<!--
body {background-image:URL('back.gif');background-attachment:fixed; margin:0px;padding:0px;}
#body{position:absolute;z-index:1;width:100%;}
-->
</style>
<script language="JavaScript1.2">
<!--
var oldScrollX=0;
var oldScrollY=0;
var NN=(((document.layers)?true:false) &&
navigator.appVersion.charAt(0)=="4");
function fixBg() {
if (window.pageXOffset!=oldScrollX || window.pageYOffset!=oldScrollY){
document.layers['bg'].left=oldScrollX=window.pageXOffset;
document.layers['bg'].top=oldScrollY=window.pageYOffset;
}
}
function makeBg() {
if (NN) {
document.layers['bg'] = new Layer(window.innerWidth);
document.layers['bg'].left = 0;
document.layers['bg'].top = 0;
document.layers['bg'].height = window.innerHeight;
document.layers['bg'].background.src = 'back.gif';
document.layers['bg'].visibility = 'show';
document.layers['bg'].zIndex = 0;
document.layers['bg'].document.open();
document.layers['bg'].document.write('<table width="100%" '+
'height="105%" border="0" cellspacing="0" cellpadding="0">'+
'<tr><td> </td></tr></table>')
document.layers['bg'].document.close();
setInterval("fixBg();",100);
}
}
//-->
</script>
</head>
<body leftmargin="0" topmargin="0" rightmargin="0" bottommargin="0" marginwidth="0" marginheight="0" background="back.gif" bgproperties="fixed" onLoad="makeBg();">
<script language="JavaScript1.2"><!--
if (NN) document.write('<div id="body">')
//--></script>
<script language="JavaScript1.2"><!--
if (NN) document.write('</div><table height="NNNN">'+
// ^^^^
//Здесь пишем высоту странички в пикселах при разрешении 640x480
'<tr><td> </td></tr></table>');
//--></script></body>
</html>