I need a website designed to allow different users to visit different parts of a website (categories from a list). A user should be able to pay for access through paypal and google checkout and at that time determine a username and password. The username and password should immediately allow the user to access that part of the website. The access should have a changeable timeframe that the username/password is valid. I would like to be able to change all of these variables through some admin screens. I need to be able to easily add new categories and subcategories through the admin screens. I think I would like it to be in PHP but I would certainly consider others.