Also, be careful how you use the knife tool because Blender can't handle Ngons or faces that have more than four verts.

Most of the subdivision, to keep everything uniform, will be done with loop.

The one really annoying aspect about Blender's knife tool is that it puts itself back away again after one slice.

Also, for the person whom wrote the opening post, If you want a really good, freeware, NURBS / Spline modeler check out Marble Clay 3D http://homepage3.nifty.com/escargot/MCLFrm.html