Also if you're new to NURBS modeling but have previous experience doing sub-d polygon modeling, check out here for some links to discussion and tips for people who are coming from that kind of background:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

NURBS modeling has a pretty different approach from polygon modeling and it can be problematic to try and use poly modeling strategies instead.

One of the main differences is that booleans and intersection methods are a primary way to do stuff with NURBS modeling, and instead of manually drawing every single final edge of your model to start with you usually instead want to draw primary profiles that make extended basic shapes and have other portions of the end 3D model come from intersections with other objects or profile curves.

I've noticed that often times people from a sub-d modeling background try to draw in a big network of curves to start with rather than using booleans.

- Michael