I've installed Google Desktop Search, Yahoo Desktop Search, and MSN Desktop Search. They all pretty much work as advertised. Google is the fastest and has a slick integration with the google.com search page. MSN looks pretty but is very slow and slim on functionality; my advice is to skip it. Yahoo has an Outlook plug-in and (while not as fast as Google) is fast enough and has the best previewing of any of them. Bottom line: Yahoo has the best overall desktop search app.