I don't know about the 64 vs 32 bit thing (I would also like to know this though

)
But for a window manager, depending on your tastes and CPU power, I would say Gnome & Beryl
or Enlightenment (What I am running now- see the Linux gallery for a screenshot)
Like the answers I have had here, best thing just seems to be to install a few and see what you like best!