Nurbs to poly to sub-d

Best thing to do with nurbs is to use the simplest modeling form you can. Usually i start off with a primative.

Convert to poly and attach all the vertices up that line up. Try various types of conversion to ensure that you dont get 3gons or 5gons, you only want 4 sided poly patches.

Do Not Smooth... unless you intend on staying with polygon surfaces. Smooth will add too much unnecessary geometry for sub-d surface conversion.

Convert to sub d and add additional geometry in either Poly Proxy mode or in refined vertice mode.