what most people seem to feel is that if you get through Lammle's material you'll be able to get through anything on the exams. To give you an example of how precise he is with things, the subnetting section is so comprehensive that it covers every possible kind of mask you will ever encounter (including the .128's that you wont see on the Cisco tests).
I would just check to make sure you have the most relevant book, they keep modifying the exams, so you should check the topics covered on the cisco site and then see if your books have it all. If something seems to be missing, use another book or google (or post here). There is no such thing as the perfect book for the CCNA, but I'll tell you this much, for 640-607, there was no better book (I have been through almost all the most highly recommended ones). The stuff I picked up from Lammle's books have stuck with me till today... I still calculate subnets using his methods and shortcuts.. (the 'subnetting in your head' section of the book).
Couple Lammle's book with the stuff on this site, a real router or decent router sim, and the practice tests / labs on
and I'll bet you my favourite box (a really nicely done up RH9/XP box affectionately called 'lara') that you'll pass. And if you don't get a really good score, I'll throw in the secret firewall.cx video of tfs parking his dirt bike.