Sharepoint 2010 primary search result should be document file name and title as the secondary?

Hi Guys,

Currently the search results from SharePoint are based on the Document Title. Due to the fact that most people have not entered anything into this field we wish to change this to the Document File Name as the primary search result with document title as the secondary key.

Could you please help me how to change the search result should primary as name and title is secondary result.

Cheers

Suresh