window.onload = moveIt(document.getElementById('content')); 
function moveIt(obj) {
	toppos = 0;
	leftpos = 0;
	toppos = window.innerHeight ? window.innerHeight : document.documentElement.clientHeight ? document.documentElement.clientHeight : document.body.clientHeight;
	toppos = toppos/2-300;
	leftpos = window.innerWidth ? window.innerWidth : document.documentElement.clientWidth ? document.documentElement.clientWidth : document.body.clientWidth;
	leftpos = leftpos/2 - 600;
	obj.style.position = "absolute";
	if(toppos < 0) obj.style.top = "0px";
	else obj.style.top = toppos+"px";
	if(leftpos < 0) obj.style.left = "0px";
	else obj.style.left = leftpos+"px";
}