While housecleaning recently, I went through a shelf full of my old computers books. After price checking them against several online services, as well as seeing as what they were selling for, I ended up with .., nothing. This shelf-ful of books, worth at list price over $500, which I paid at least $200 for is now worth absolutely nothing in several short years. Makes you thing twice about buying computer books.
P.S. And of course they are all available on the Kindle.