The settings of the different search-related features available in the search engine of Office SharePoint Server 2007 are managed at three different levels. The first and topmost level is the farm level, with settings that apply across all instances of SSPs. The second level is that of a single SSP instance, which allows you to manage settings separately for each instance. The third level is at the site collection. The available settings for each level are listed here.
Farm level. SharePoint farm administrators can
Start and configure the Search service on index and query servers in the farm.
Create and configure new SSPs.
Configure proxy settings to have some or all content crawled through a proxy server. ...