First of all...one thing is not true...there's also a possibility to create a nurbs surface, which is only one object....I created a small animated gif for you...I created the circles...duplicated them, and moved them up...afterwards i created a loft with the outer circles and after that a loft with the inner circles...Now create a loft between the outer and the inner ring. In my case I added some isoparms, to create a round edge afterwards. not attach the surfaces, using the blend option. Connect all surfaces and at least Nurbs->open/close surface, with selected "V". Now you delete history, delete all curves..and you have one, clean nurbs-object, without having to convert it to Polys.

hope that helps...

b u l l e t