Copernic Desktop Search
Copernic develops cutting-edge information management software that enable pc users to access, find, manage and even discover information they need. makers of copernic agent, copernic desktop search, copernic tracker and copernic summarizer.
http://www.copernic.com/
Google Desktop
Google Desktop
http://desktop.google.com/
Windows Desktop Search
Windows search provides an easy and comprehensive solution for finding and organizing the content you care about, no matter where it lives.
http://www.microsoft.com/windows/desktopsearch/default.mspx