So I was using a music download program which also downloads videos and documents. I typed in 'Terry Pratchett' to see what came up. There were over 200 files, ranging from aduiobooks to ebooks.

I clicked on a file called simply Terry Pratchett. When it opened, it contains ebooks of the fist 26 Discworld books, Monstrous Regiment & The Unadulterated Cat.

Didn't PTerry refuse to do ebooks?!

It only takes one idiot with a scanner and patience.

But how do you scan only the text and not the paper (background) from the book as well?

Text recognition software. It looks over the scanned image and can recognize the text from the pages, which it converts to ASCII form.

As for the audiobooks, there are legitimate copies of them, which can be downloaded. However, these are supposed to be paid for, using programs like iTunes.