I went from Avid to FCP a few years back and now I work on both. They both have thier advantages and thier disadvantages. FCP tends to be a little more free, while AVID tends to be a little more regimented on how things are done. But once you know one the other is a lot eaiser to pick up. There are some great books that give tips and shortcuts for both programs.
Good luck,
crjoe