Jesdanun found the Yahoo engine the most practical and easy to use, but all three engines are still in beta testing. All three have the ability to search instant message conversations, but Yahoo and Microsoft can search only their respective messaging programs.
Of the three desktop search programs, the Microsoft Corp. and Yahoo Inc. products differ slightly in how they approach your data, while the Google Inc. alternative diverges quite a lot.
Which one is right for you comes down to your needs and regard for privacy.
Microsoft's MSN Desktop Search, which is part of the MSN Toolbar Suite, and Yahoo Desktop Search are still ``beta,'' or test, products, which could explain why Yahoo kept crashing on one work machine while MSN refused to index my laptop.
For music, photos and video, the programs look for ``metatags'' that carry song names and other descriptions.
Google officials refused to provide a full list, but the company's Web site lists more than a dozen, the ones you're most likely to need.
MSN and Google also let outside developers make plug-ins for unsupported formats.
All three programs index e-mail using Microsoft's Outlook and Outlook Express software, but Google goes further in handling Mozilla-based products, including Netscape and Thunderbird.
Yahoo also scans attachments, while the other two only capture their file names (though MSN lets you change a setting for full scanning).
Yahoo, which licenses technology from the startup X1 Technologies, was the most comprehensive under default configurations, finding twice as many files on one machine as Google while taking about half the time.
Yahoo is a bit better than MSN - Yahoo won't record any IM chats by default, and like Google, it lets you exclude certain file types from indexing.
All three programs have deskbars - small boxes that sit anchored to the bottom of your computer screen - from which you enter search terms.
You see spreadsheets as spreadsheets, not mangled text.
All three programs handle the basics well, so your choice may ultimately come down to what e-mail and IM programs you use and whether you care about Google's retention of deleted files.