SharePoint 2010 Department Wise site

I am new to SharePoint 2010 and I have to develop a portal for my company which has several departments. I've created a HomePage now I want to come up like the following navigation.

Departments

        Finance

        Marketing

 开发者_如何学Python;       Sales

             South Zone

             East Zone

What should I do now? Create Site collection as "Department"? and Finance and marketing and sales would be sub-sites? Can anyone please mention as per my hirerchy what should be the each site I mean which one should be site collection and which one should be sb-site....and also how to make this top navigation as appear to be fly-out menu rather than tab based.

Thanks

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The default navigation controls in sharepoint are per site collection. If you create different site collections the navigation controls wont show the links to the deparment sites. However you can customize the navigation controls.

This decision should not be depending on the navigation but more in the technical requirements, is each deparment going to have many users? many concurrent users? many data?

Remember that one web application can have many site collections, but the Sharepoint Database is created per Web Application, not per site collection.

For a Fly-Out Menu, you have to do it your self, you need to create a Menu webpart and replace the existing one, you need to customize the masterpage, comment the webparts related to menu and put yours there.