I worked with a group of animators a few years ago. We used SoftImage, a Hollywood level animation package with a learning curve that makes the Rocky Mountains look like Kansas. I messed with it a bit, but being graphically challenged, most of my work dealt with the software that used the MPEG and JPEG files we produced. It was a fun project - we were making multimedia training software to teach aircraft (and especially helicopter) recognition to fighter pilots. It was a great job while it lasted.

NURBS (Non-Uniform Rational B-Splines) are complex mathematically but not hard to understand conceptually. It uses mathematical equations to define the models instead of polygons. The models can be very precise - there was a project underway several years ago to use NURBS models to accurately calculate radar cross sections of military vehicles. The project seemed to work.

Rhino3D looks like a fun package. I could get it with a faculty discount for under $200. However, I'm still graphically challenged so I don't think I'd have a lot of use for it.