Assuming we move Scalabrine - currently our fourth big - and are planning to keep five on the team, I am in favor of adding a rotation big and a project big. One each, in order:
Rotation - Nesterovic, Smith, Oberto
Projects - Williams, Swift, Diogu
Quick note on Williams. He has proven two things in this league; He is a widebody (6'9" 250) and he can rebound (17.5 rebound rate, 12 per 40 last season). Those are valuable skills. If Cliff Ray can teach him the same hook shot and 12' he has shown Perk and Davis he will be a very productive backup for a very long time.