CompTIA Security+: Get Certified Get Ahead: SY0-201 Study Guide" from Amazon for the Kindle. On more than one occasion I've seen Gibson's books recommended as the only material needed to pass the Security+ exam. He has some (3) videos up on youtube covering some of the material for passing the exam as well.Here is the clip on Hashing:
I've started to skim the Gibson material and took a 66% on the initial practice test (85% required to pass). I will get into full swing after passing the CCNA. This will be interesting to see how it goes through the holidays. I'm thinking the down time will give me time to read / study more. Well, hopefully.
As a side note, if you'r looking to take the SY0-301, the updated Security+ exam, Gibson's new book is out in print and discounted for a limited time. See his blog post here for more information.