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?