well, for my most basic vertex-pushing I use AC3D... then it gets packed off to Carrara Studio if I need to tweak, NURB, or do anything boolean to it, saving the results in .obj format. After that, I shove it into Poser, where I can assign materials, set the hierarchy, and finalize it.

If I run into any problems, like needing a convex hull or to work with it in .3ds first, I may put it into OpenFX, a freeware modeller... it does imports vastly better than anything I've ever seen :)

Once everything is modelled, I use Poser to put it together, but then put it all back into Carrara for rendering :)

HTH a little...
/P