As a follow-up - I was talking with someone recently who has bad eyesight, and they showed me -
http://www.naturalreaders.com/. (I'm sure there are other products on the market too!)
For $50ish (£24.30), this software will read out anything copied into the clipboard. It will work for free, but the voices aren't so great. The best ones are "Kate" and "Paul" and samples can be heard on the website.
As an experiment, I put chapter 1 of a pdf file of a technical book I'm reading through it. This program allows you to export to mp3 and it came out at 90ish mins. I sped it up (so it would fit on a cd), and then split the mp3 into 1 minute tracks (so it's easy to manipulate) and tried it in the car this morning.
I think it worked really well. It occasionally gets confused (don't = "don-tea") and obviously the code samples aren't so great, but as a review the following morning of a chapter I read last night, I'd say it was excellent.
Just thought I'd pass that on for anyone who's interested. :-)