Rather than restricting a websearch to any one search engine, the Copernic Agent collates results from several different search engines for the best results.

According to the Copernic website, more than 90 search engines are quieried with any duplicated.

The Agent does more than just display the search results. You can search within the results and check that the links are valid before clicking on them. Searches can also be restricted to particular categories.

This is the free version of the software. The Personal and Professional versions have more advanced search options and cost $30 and $80 respectively.