function popUp(URL,name,W,H) {
	x = (640 - W)/2, y = (480 - H)/2;

    if (screen) {
        y = (screen.availHeight - H)/2;
        x = (screen.availWidth - W)/2;
    }
	myWindow = open(URL,name,'toolbar=0,directories=0,scrollbars=1,location=0,statusbar=1,menubar=0,resizable=1,width='+W+',height='+H+',screenX='+x+',screenY='+y+',top='+y+',left='+x);
	return false;
}