NAT was on my BCSI exam. It was the the central topic in one of my simulation questions.
As far as preping, I used the latest Cisco Press book, It's a long read but covers the materials very well. I'd recommend getting some hands on experience with setting up the routing protocols with either some real equipment or a rack rental. I'd suggest getting your hands on some equipment or a rack rental for all of the CCNP exams.
Network Admin
CCNP
Cisco Firewall Spec.
Cisco IDS Spec.
MCSA