If free apps is what you want there is quite a list of things that you can try out.
Moi 3d will cover your nurbs work..
Kerkythea is an excellent render engine and I do most of my renderings in there its also very easy to use.
If you want a full 3d software and dont get around Blender that fast you can use the now free Truespace 7.6.
It also has 2 render engines incorporated Lightworks and Virtuallight.
Then there is Wings3d which is a very basic but also pretty easy to use polygon modeler.
But on top of all that there is Sketchup from Google which also comes in a free version and can be rendered in Kerkythea too.
The Moi 3d beta now also exports to Sketchup which is a great bonus !
So you see there are pretty many options all free and most very easy to use and learn...
Peter