Hi Robert

I'm quite partial to C4D for rendering my Poser images.  Besides having better lighitng abilities than Poser it'll also import lots of other file types (eg: 3ds, LWO etc), you can simulate cloth, do modelling etc...  A good example of Poser done in C4D is Kromekat's gallery - he does tutes on these in 3DWorld mag.  (I've also got some images in my gallery... but check out Kromekat's first!)

It depends on what you mean by "realistic" as Poser figures will only ever be as "real" as their textures - some of the work in Poser itself is amazing because the textures are so good (see FS's gallery) but I struggle with getting anything I'm happy with out of Poser itself.

Anyway, you can import scenes into C4D using Kuroyume's InterPoserPro (still in beta but due out soon) which you can either lift complete Poser scenes or individual characters and props and pose them in C4D (see http://www.kuroyumes-developmentzone.com/) 

cheers - Alan42