People who use public or workplace computers for e-mail, instant messaging and Web searching have a new friend: Google's free new tool that indexes a PC's contents for quickly locating data.

'It's clearly a very powerful tool for locating information on the computer,' said Richard M. Smith, a privacy and security consultant in Cambridge, Mass.

Google Desktop Search, publicly released Thursday in a 'beta' test phase for computers running the latest Windows operating systems, automatically records e-mail you read through Outlook, Outlook Express or the Internet Explorer browser. It also saves copies of Web pages you view through IE and chat conversations using America Online Inc.'s instant-messaging software. And it finds Word, Excel and PowerPoint files stored on the computer.

The software is helpful 'as a photographic memory of everything you've seen on the computer,' said Marissa Mayer, director of consumer Web products at Google Inc.

The giant index remains on the computer and isn't shared with Google. The company can't access it remotely even if it gets a subpoena ordering it to do so, Mayer said.

Although the software can be used to spy on oother peoeple, Google does not intend for it to be used in that way and discourages people from downloading the software on a shared computer.