The Creepest Movie Ever

According to Wikipedia, this 2006 horror flick starring Donald Sutherland and Sissy Spacek is based on true historical events that were described in the novel The Bell Witch: An American Haunting, by Brent Monahan.
The event described are based around the legend of the Bell Witch.
True or not? I won't try to decided that but it is, without doubt, one very creepy movie.
Check out this trailer: