
If I replace what books I used to have with the new stuff, I'd end up spending more than the things I wanted to build would cost retail.
+1. Not only for portability (I have all of my e-books on my tablet and phone in addition the desktop and backup drive). They are on the phone even though I don't really like reading on it as a back up for the tablet (I can always swap out the SD drive if I need to on the road) but also to have reference/equipment manuals with me at all times if something comes up on an Amateur radio event in the field (and don't want to dig out the paper manuals, besides key word search works so much better on an e-book than a hard copy).