var wWidth = 640;
var wHeight = 410;

function popupWindow(URL, newWidth, newHeight, windowName) {
	if (newWidth && newHeight) {
		var wWidth = newWidth;
		var wHeight = newHeight;
	}

	popupWindowFeatures = "height=" + wHeight + ",width=" + wWidth + ",resizable=yes,toolbar=no,scrollbars=no";

	if (!windowName) { var popupWindowHandle = window.open(URL, "popupWindow", popupWindowFeatures) }
	else { var popupWindowHandle = window.open(URL, windowName, popupWindowFeatures) }

	popupWindowHandle.focus();

	if (parseInt(navigator.appVersion) >= 4) {
		var sWidth = screen.width;
		var sHeight = screen.height;
		popupWindowHandle.moveTo(sWidth / 2 - wWidth / 2, sHeight / 2 - wHeight / 2);
	}

	return false;
}