That’s what I’m going through right now. I’ve got a book length story in mind. Got it all outlined out, but I just can’t get the damned thing started. I may have to use one of those programs that helps you design it scene by scene. Luckily, I have two of those.
One of them is called yWriter, and is up to version 5. It can be found at www.spacejock.com. One good thing about it is that the guy who wrote it is also an author, so he wrote it for people like him.
The other one is called Storybook (or to be precise StorYBook – no idea why the Y is captialized), and that can be found at http://storybook.intertec.ch/joomla/. Note that you’ll need Java installed for this one to work.
If you’re interested, give ’em both a look. I use different aspects of both of them.
Now to open them and start writing, damnit.