// get position of element by id elem
function GetPos(elem)
{
var offTrial=document.getElementById(elem);
var offL=0;
var offT=0;

while(offTrial)
{
offL+=offTrial.offsetLeft;
offT+=offTrial.offsetTop;
offTrial=offTrial.offsetParent;
}

if (navigator.userAgent.indexOf("Mac")!=-1 && typeof document.body.leftMargin!="undefined")
{
offL+=document.body.leftMargin;
offT+=document.body.topMargin;
}

return {left:offL , top:offT}
}



вызов
var p1=GetPos(obj.id)

document.getElementById(p5).style.top=p1.top +25 ;
document.getElementById(p5).style.left=p1.left;