Geoffrey of Monmouth, The History of the Kings of Britain
David Trottier, The Screenwriter's Bible: A Complete Guide to Writing, Formatting, and Selling Your Script
I've read the former but never owned a copy of it.
Anyway, we've been knocking around the idea of a screenplay for a while. Thought we might at least get some idea of how the process works.
Addendum: If anyone has any recommendations re: screenwriting software, I sure would appreciate the advice.