I've worked at a prison for a couple of years now, and have tried to help encourage the inmates to read - it keeps them from being "bored" and getting into trouble, provides them with some knowledge, and gives them something more to talk about with other people than "thug life". The books wear out quickly for two reasons: 1) they're used, donated books to begin with. 2) they're read and shared A LOT. Especially when there is very little else to do.
They do get thrown about from time to time (by officers searching their cells, or as emergency "body armor" if things are about to jump off), but generally books are respected as they can be. Sure, some hide contraband in them (usually ineffective, at least in the cell searches I've seen - the officers have seen the same bad movies about prison you have). People are most likely asking for computer books because they're legitimately interested in the subject area. If they're looking for generic, thick books, they could easily have access to a Bible or other classic book of literature. (I suddenly have the image of an inmate saying, "Sure, I'll read 'War and Peace' it's not like I don't have the time anymore." :) )