I only read public domain books from gutenberg.org (more than enough great material to read 20 hours a day until you die), and PDFs I download here and there.

I only read public domain books from gutenberg.org (more than enough great material to read 20 hours a day until you die), and PDFs I download here and there. I simply copied them the the PRS using it as USB storage, usually, though now I'm using Calibre to keep a list of what's on my reader and organize it.