Dell, the world's second largest manufacturer of PCs and laptops, is testing a software package developed by Google which would be pre-installed on 100 million new computers.

The move is the latest challenge to Microsoft, the world's largest software developer, for control over computer-users' desktops.

A spokesman for Dell said the company was looking at Google software that would be used to search the internet and the information stored on an individual computers' hard drives.

"We can confirm that we are running a test with Google that could include a Google-powered Dell home page, Google desktop search and a Google Toolbar," he told Reuters.

A Google spokesman told Times Online: "We are testing the distribution of various technologies with Dell."

Unconfirmed reports have suggested that Dell and Google are in talks to put Google software on as many as 100 million Dell PCs. The move is thought to have followed a bidding process in which Google edged out Microsoft after Yahoo!, the third major player in the market, pulled out.

Google already has deals in place with software developers such as the Mozilla Foundation under which its website is pre-installed as the homepage on the company's Firefox browser. The revenues from such deals have proved significant money spinners for Google's partners.

Analysts said a fall in the price of Google's shares overnight reflected concerns that signing major deals with PC manufacturers would see Google's cost of acquiring new users increase dramatically.

Google shares fell $17.18 in New York overnight, to close at $367.92. The stock, which recently tested $460, plunged last week after the company missed Wall Street's ambitious fourth-quarter profits targets.

Microsoft itself used the pre-installation of its products to promote the use of its Internet Explorer in the 1990s. It included the web browser for free with its Windows operating system in a move which crowded the then market leader, Netscape, out of the market.

However, it is unclear whether the Google-Dell tie-up will actually involve the development of new products. Google already has toolbar and desktop search systems in the market. So far, Google's offerings fall someway short of representing an operating system that would rival Microsoft's dominant Windows product.

Shares in Microsoft closed down 23 cents, at $26.94.

To have your own say on Google, visit the Times Online technology blog.

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