var na_ipX = (screen.width/2)-320;
var na_ipY = (screen.height/2)-240;
var pos = "left="+na_ipX+",top="+na_ipY;
function na_ip(){
na_ipWindow = window.open("http://www.na.org/ips/eng/IP1.htm","na_ip","scrollbars=yes,width=640,height=480,"+pos);
}