After creating your first SharePoint 2007 site collection depending on the template you selected you may not see the search scope options of "All Sites" or "People" in your search scope dropdown. To make those scopes show up you need to make sure you have a search center site created. Once you have a search center site you will want to go into your site collection administration, select search settings, and then select the option to use custom scopes. You will need to provide the path to your search center site. Once you do this you should now see the "All Sites" and "People" search scopes in your drop down search scope list.