Hi mot! I like your name -- Word!
You can always keep your Kindle books for the LCD side and get/buy/borrow epubs to read on the e-ink side. Of course, if you have a large library of Kindle books waiting to be read that doesn't help much.
If you decide to convert your books in Calibre it is easy to upload them onto your device using the USB cable. Calibre recognizes the PE and will show you on your computer what books you have on your PE. Or you can transfer them wirelessly over a LAN.
Good luck! Feel free to ask if you have questions.
