If Two Towers wins a major award, it will be for best director and best adapted screenplay, it wont win best picture, best actor, or best actress. It likely wont be nominated for the later two. It might have chance at Best Supporting Actor. They are trying to get Gollum some kind of nomination(seriously), but thats unlikely even though Gollum is eligable for either acting nod(best actor and best supporting actor), any of the live actors could get best supporting nods, I dont think any will best actor nods.
It will win best special effects, best editing, has a chance at best cinematography, best sound, best sound editing, best score.
It will take alot of awards home from the technical(non televised portion) awards.