The fiscal period setup window shows the BEGINNING date for each period. If November shows 11/30/2009, that means November actually starts on 11/30/2009. I am enclosing a screenshot of what a calendar year fiscal year looks like.
If you are still having issues with FRx picking up the wrong dates, go to the company setup in FRx, choose the company the changes were made in and click Set as Default. That should rebuild the GL index used by FRx with the new fiscal year information.