This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
In the nbproject (short for "NetBeans Project") folder NetBeans saves some configuration-stuff for profiling-settings, build-scripts, etc. So you shouldn't remove it if you want to continue NetBeans as your IDE. (Even though it's good practice to have a build script which is independent from your IDE)