@RоryMcCune I once knew a web developer who strenuously argued for using ancient machines as web servers in dev/test, to ensure that the apps would perform well in production on modern machines. I don't know that he got a lot of traction in the community at large, but it's hard to argue that it wouldn't work. It certainly did for him.
@Simon So, my experience is limited, but I've taken a few of the practice sets of questions I've found here and there, and am thoroughly confident that I could pass it without either a book or a class. So yes, I'd say that it's entirely possibly to pass with a book alone. Whether it's worth it or not, I would say depends on what field of infosec you're leaning toward. If you want to do enterprise security, I think it'd probably be a good way to help get a foot in the door.
@Simon If you're looking to do something else, like pen-testing or application security, not as much, from what I've seen.