Originally Posted by Kumabjorn
As for the K4B and KPW difference, seems to me a lot of those differences are in software, so no reason the K4B couldn't be upgraded to provide the same experience, sans light and resolution.
The biggest difference is that the KPW is a touch-screen reader. It also has a new screen with better resolution, and of course, the built in light. The battery life is better than the K4B too...