Do I really need a Portal ??
Always one question comes to my mind , why do people go for Portal development , can't they manage with a normal web aplication , managing the UI Page with different sections? I am sorry if my question is not valid.
Or In what scenarios do we actually need a web Portal?
Managing a UI page with different sections is fine if your users are using only your application. However, a portal allows your users to use multiple applications (and many of them not created by you) and kind of 'aggregate' their content on one page; well at least have a place which provides easy access to them on one page. The emphasis here is on multiple applications; these are applications that you as a developer may have no control over; they may have been written by a third party (such as Google, or any other developer).
The items on a portal page may not necessarily be from the problem domain that you are developing for. There's no reason why a user can't put the local weather on the same page that he's examining the inventory for his company.
Portals provide a single point of entry; that's the key point. A portal also provides some other niceties such as managed logins. If you are creating an application for a customer, and you don't have a need for a portal, a portal may be overkill (and probably is, if you have to ask).