I had a look at that book and their page doesn't say anything about not
being available in format 4. So if you found out only after purchase, even
if it was free, I would call and see if they will give you another book. Not
sure why that book wouldn't be in format 4 since it was published by Warner
Audio in 2005. You could play it in windows media and use their speech
compression. The other annoyance is that it is abridged.
