Yahoo is set to launch the first upgrade to its desktop search tool, adding the ability to index data from Yahoo's instant messenger archives stored on users' PCs and from users' address books residing on Yahoo's servers.

In its first, beta, version, the product could only index information found on users' hard drives, but now Yahoo has built a bridge between the tool and Yahoo's servers, said Bradley Horowitz, the company's director of media and desktop search.

Although the only Yahoo online data available now is the address book information, Yahoo will add links between the desktop search tool and other server-based data, such as web mail, calendar and photo album, he said.

Ultimately, the goal is to have the tool index a user's data whether it is stored on his PC hard drive or on Yahoo's servers, he said. "That's the direction in which we're moving," Horowitz said. "This is the first bridge between local and server-based content."

Yahoo hasn't decided yet whether it will enable the tool to tap into data stored on competitors' servers, such as web mail services other than its own, Horowitz said.

In order to have the tool index data from Yahoo's servers, users have to activate a feature which asks for their Yahoo ID and password, he said.

The tool is still useful for those users who just want to index data stored on their PCs, he said. For example, Yahoo Messenger sessions are archived locally, and this new version of the tool can index that data.

Like other desktop search tools, the Yahoo product, which can be downloaded here can index a plethora of other local information, including word processing and spreadsheet documents, downloaded e-mail messages and images.

The Yahoo Desktop Search tool is based on technology from X1 Technologies, which sells a desktop search product tailored for business users, a market Yahoo isn't pursuing, Horowitz said.

Desktop search tools in general are designed to help users find information stored on their local hard disk drives, although increasingly these products are reaching out into data stored beyond the PC's boundaries.