Here's a link to the official DMV practice test:
NCDOT: Driver Knowledge Sample Test
and one of the site's that's often posted as a good read for practice:
Steve's Online Brain Dump » North Carolina DMV Driver’s License Test Study Guide
I've been licensed in three states (Georgia, North Carolina, and California), and NC has by far the most poorly-written licensing test I've ever encountered. It hasn't changed much between the first time I took it (1993) and the most recent time (2008) except for changing from paper-based to automated. With that said, it's not difficult by any stretch of the imagination, especially if you use those two websites.
Good luck!