Advanced user permissions

Hello,

I’m trying to demonstrate in my company, that open-source projects can be as good or better than comercial products.
So i have an installation of wordpress, but now i need to get some advanced user permissions set up.
What i want is :
– i need to have a user that can create any kind of categories,articles,pages
– i need to setup up a administrator for each departament in the company, and that user can only manage the categories,articles,pages whithin that departament

For example let’s assume ACME Co with 2 departments :
– Finance
– Marketing

The administrator will create 2 categories of pages , the Finance and Marketing. In each categorie this administrator will be able to create any sort of sub-categories,articles,pages.
The category Finance will have an administrator that will be able to create any sort of sub-categories,articles,pages but in Finance category only, and the same applies for the Marketing.

I hope i made myself clear, and thanks for your time and support.

Best regards,
Bruno Sousa