var myPop = null;
var option = "toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=0,resizable=1";

var w = 750;
var h = 600;

function popUp(address)
{    

	if (myPop && !myPop.closed)
		myPop.close();
	
	option = option+",width="+w+",height="+h;
	myPop = window.open(address, "what_I_want", option);

	
	if (myPop) return false;
}