This blog posting applies to Microsoft Office SharePoint Server 2007.
The term “Area” is no longer used in MOSS 2007. Areas were implemented as subsites, however, and it is still possible to create subsites on the Portal. The ability to manage the hierarchy and navigation of subsites replaces the ability to reorganize Topic Areas on 2003. Navigation links to subsites now may appear as tabs and as left-column links, mirroring the old Topic navigation methods, but are more flexible in what can be displayed where and in what position.
In MOSS 2007, you still have the concept of content sources and search scopes, but they are both more flexible. But you don’t administer them from the portal. You must go to the shared service provider administration page to create content sources. To do this, go to the central administration pages then click Shared Services Provider link in the left nav column. Content sources are lists of URLs at which search crawls are to begin; you can specify your entire site, or a series of special subsites on the portal that you want to search. You must do this to ensure the content on your subsites makes it into the index. Then, search scopes specify what portions of that index to retrieve results from. Scopes can be defined by what content source put them there, or by URL path with wildcard, or by filtering against a value such as contenttype or author.
Set these both up on the shared services provider administration pages, then go to your portal and choose which source scope(s) you want to include in your search control.