One month after announcing its plans to test a desktop search application, Yahoo! has joined frontrunners Microsoft and Google in their efforts to index and search hard drives as efficiently as they do the Web. But unlike its rivals, Yahoo! has not developed its own desktop search, instead the licensing technology from X1.

The Yahoo! Desktop Search beta searches over 200 file types, the company says, including Word, Excel, PowerPoint, PDF, text, HTML, and ZIP files. E-mails within Outlook or Outlook Express are also indexed, along with the contents of attachments.

Yahoo! touts more advanced filtering over competitors, but its desktop search does not integrate Web searches as Microsoft and Google have done. Rather than a toolbar, Yahoo!'s offering utilizes a full application, with tabs for different types of files and a built in preview window.

Although it is relying on search provider X1 Technologies to build its new application, Yahoo! is confident it can succeed in an already crowded market. The company plans to evaluate response to the beta release and expand the capabilities of its desktop search.

But competition is heating from all sides, as Microsoft's delay of Longhorn has opened the door for third parties to capitalize on lackluster search support within Windows. Search providers Ask Jeeves and AOL are testing the desktop search waters with beta releases, while newcomers Copernic and Mac-based Blinkx also vie for a piece of the market.

Yahoo! Desktop Search is available for download via FileForum.