secure area for certain users

Hi all,

I’m looking to use wordpress to build a website for a small business.
Ideally what I am looking to do is have a public site, with a secure area for staff to see confidential/internal information.

As a public viewer all you will see is a “staff login” button, but once logged in you will see an additional or completely new menu structure and pages containing the staff only info.

I have a demo site setup and been playing with numnerous plugins for various bits and pieces, and to be honest I’ve just got myself confused now so I’m starting again, this time hopefully with some input from the experts on how they might acheieve what I want.

thansk