var ns4 = (document.layers);
var ie4 = (document.all && !document.getElementById);
var ie5 = (document.all && document.getElementById);
var ns6 = (!document.all && document.getElementById);

function grabStyle(id)
{
   if(ns4)             return document.layers[id].style;
   else if(ie4)        return document.all[id].style;
   else if(ie5 || ns6) return document.getElementById(id).style;
}

function grabObject(id)
{
   if(ns4)             return document.layers[id];
   else if(ie4)        return document.all[id];
   else if(ie5 || ns6) return document.getElementById(id);
}

function position()
{
   var width=document.body.clientWidth;
   var height=document.body.clientHeight;

   var mainTableObj=grabStyle("mainTable");
   mainTableObj.top=height/2-600/2;
   mainTableObj.left=width/2-770/2;
   mainTableObj.position="absolute";
}
function changePage(pageStr)
{
  var obj = grabObject("page");
  obj.src = pageStr;
}