There's 3 Exorcists movies. The first one is easily the best. The second one is called Exorcist II: The Heretic and the third one is The Exorcist III (how original... ). Don't ever waste your time to watch the second one...it's one of the worst movies I have ever seen in my life (and I have seen MANY). The third one is entertaining but not nearly as good as the first one.
The Exorcist just made me laugh, the only creepy bit was at the start of the film with those sounds coming from the attic. The rest just tickled my funny bone