Probably one of the least understood areas of SharePoint administration.

At our Summit Administration tracks we usually spend almost a full day on search.

Search scopes  are built from the ground up.

First one creates a content  index which requires assignment to a source group.

I suggest creating a source group for indexes which is never to be used in creating a search  scope.

Why you ask. Thank you for asking.

Multiple content sources can be stored in the same index.

If you then uses a source group that includes an index in building a search scope, all content sources contained in that index will be included in the search scope.

Next, one creates the content source which requires assignment to a source group.

I prefer individual source groups for each content source.

This now permits me total granularity in building search scopes that include the particular areas and content sources (via source groups) that I want assigned to that search scope.

To index only .doc files is managed in the content index.

To include only portal  content in a search scope, create the search scope using only the “portal content” content source via the assigned source group.

I hope this was helpful and not more confusing. Bill will cover this Friday again I am sure, but maybe this gives you a head start.