Don't want this to be a Zombie thread, but I do have relevant info.

The main problem with using a netbook is that they still don't have the battery life. The Kindle uses electronic ink, which requires very little. In fact, it requires next to none until you turn the page.

I personally use my GBA/DS. They've got the battery life when reading books. And the flashcart you use to load the books can also be used to load games. You can not only play native games, but also emulate up to the first generation SNES games (the ones without a coprocessor). Heck, my first exposure to SydLexia.com was the Top 100 NES list, as I wanted to know which ones to add to the emulator on my GBA.