function fixPosition(el,delay,offset){
  if(document.getElementById){
    el.delay=delay;
    el.initTop=0;
    el.offset=offset;
    el.refreshPosition=function(){
      if(document.getElementById){
        st = parseInt((document.documentElement.scrollTop) ? document.documentElement.scrollTop : document.body.scrollTop);
        st-=this.offset;
        if(st<0){
        	st=0;
        }
	    this.style.marginTop=this.initTop+st+"px";
      }
    }
    setInterval('document.getElementById("'+el.id+'").refreshPosition()',delay);
  }
}