Google can return a ton of hits for any query you make. To make the search really efficient, the trick is to tell Google how to scope the search so that instead of getting a billion results, you get the 100 best. In order to scope things better, Google has set up special search groups for specific topics, including information for Microsoft, Apple Macintosh, BSD, Linux, and the U.S. Government. For instance, when you search from http://www.google.com/microsoft.html, your query will be run only on sites that have predominantly Microsoft content.
To use the specific sites, point your browser at http://www.google.com/...