lastScrollY=0; 
function heartBeat2(){ 
var scrollPos; 
if (typeof window.pageYOffset != 'undefined') { 
   scrollPos = window.pageYOffset; 
} 
else if (typeof document.compatMode != 'undefined' && 
     document.compatMode != 'BackCompat') { 
   scrollPos = document.documentElement.scrollTop; 
} 
else if (typeof document.body != 'undefined') { 
   scrollPos = document.body.scrollTop; 
} 

diffY2=scrollPos;
percent2=.1*(diffY2-lastScrollY); 
if(percent2>0)percent2=Math.ceil(percent2); 
else percent2=Math.floor(percent2); 
document.all.backi.style.pixelTop+=percent2; 
lastScrollY=lastScrollY+percent2; 
} 
window.setInterval("heartBeat2()",1);