Out of necessity, the film of The Fountainhead left out a lot from the novel, as they almost always do. The producers of Atlas Shrugged hope to avoid this flaw by doing the film in several parts.
The best screen treatment of a Rand novel is Goffredo Allessandrini's 1942 version, made without Rand's approval (or even knowledge). Ironically, it was financed by the fascist Italian government, which considered the story anti-communist. When released, they wondered why it suddenly became so popular--and then realized that it was just as anti-fascist as anti-communist. The government immediately yanked it from the theaters.
I have the tape of the movie. It is of very high production values for the time, and renders Rand's semi-autobiographical novel very well onto the screen.