Have you ever wondered why Easter and Passover do not always fall together on the calendar? Some years they happen in the same week, but then other years they are a whole month apart. For example, this year Easter is on March 23, 2008, but the Passover does not begin until April 20, 2008.
It all has to do with solar years, lunar months and the Jewish leap year! You can read all about it in the following article: Determining the Dates for Easter and Passover.