Which is more important - Implementing the Business Process or Changing the Corporate Culture?

Both are important. if a company's objective is to be achieved in the short term then implementing a business process becomes more important. if the objective is in the long term range then i would go for changing the corporate culture because changing an entrenched culture is the toughest task you will face and will definitely take time. To do so, you must win the hearts and minds of the people you work with, and that takes both cunning and persuasion.