I'm a little fuzzy on the timeline for the movies... AFAIK, ep3 ends with the birth of Luke and Leia... ep4 takes place about 18-20 years later (I'm guessing at Luke's age here). It seems to me there's a whole lot going on in between the movies hinted at the beginning of ep4: the rise of the Rebellion, their first victory against the Empire, and the stealing of the Death Star's plans (which, apparently, also takes about 20 years to build). Ever wonder if George will spring an 'out of sequence' movie on us sometime to cover all this?