plot explanation - What was David's motivation in Prometheus?

For me,
perhaps the most interesting person aboard the Prometheus was the android, David. I'm
still confused by his seeming fascination with the movie, Lawrence of
Arabia. Although I couldn't make notes during the film, I believe that he
quoted Peter O'toole's character, Lawrence, on more than one occasion. Was he attempting
to attain a similar achievement with the Engineers as Lawrence did with the Arabs? Why
did he infect the Crew leader? What was his motivation?