function popUp(page, newWindowName, windowWidth, windowHeight) {

var leftprop, topprop, screenX, screenY, leftvar, rightvar;
if (navigator.appName == "Microsoft Internet Explorer") {
   screenY = document.body.offsetHeight;
   screenX = window.screen.availWidth;
} else {
   screenY = window.outerHeight
   screenX = window.outerWidth
}

leftvar = (screenX/2) - (windowWidth / 2+10);
rightvar = (screenY/2) - (windowHeight / 2+20);
if (navigator.appName == "Microsoft Internet Explorer") {
   leftprop = leftvar;
   topprop = rightvar;
} else {
   leftprop = (leftvar - pageXOffset);
   topprop = (rightvar - pageYOffset);
}

   newWindow = window.open(page,newWindowName,
           "resizable=no,status=no,location=no,directories=no,toolbar=no,menubar=no,scrollbars=no,width=" + windowWidth+ ",height=" + windowHeight+ "");
   newWindow.focus();
}