Google is famed for its Web search engine, but over the past few years it has acquired a different role: Microsoft's No. 1 foreign aid donor. First, Google fixed some of Internet Explorer's worst defects with its Google Toolbar, a free add-in that blocks pop-up ads and provides a shortcut to (naturally) Google's search engine and an auto-fill option to complete Web forms. Now it has released the Google Desktop, another free program that fixes an equally glaring weakness of Windows: its woeful file-searching capabilities.

What a wonderful favor to do: Microsoft ought to send Google a thank-you note sometime.

What Google did for Web searching, Google Desktop -- available in a beta-test form at for Windows 2000 and XP -- does for file finding. Once installed, it quickly builds a database of the non-system files on your computer's hard drive, then indexes the contents of many commonly used types of files -- Web pages viewed in Internet Explorer, e-mail read in Microsoft's Outlook and Outlook Express mail programs, America Online instant messages, Microsoft Word, Excel and PowerPoint files, and text files.

This indexing has yet to have any detectable effect on the performance of two PCs I've put Google Desktop on, despite its ludicrous speed. New e-mails turned up in Google Desktop's search results within six minutes of their arrival, and freshly viewed Web pages were indexed even faster, within about 10 seconds.

Since Google Desktop's index is updated so often, it also tracks changes to text and Microsoft Office files. Click a file's name in a Google Desktop window to open that file in whatever program created it; click the "cached" link to view older versions within your browser window. Only the text of them appears, which works fine for most Word and text documents; Excel and PowerPoint files, however, usually look like gibberish without their formatting and graphics.

Google Desktop requires 500 megabytes of free disk space to install, but it doesn't seem to use much space in practice -- just 120 megabytes or so of data on the machine I'm using now.

Google Desktop's advantage doesn't always lie in the speed with which it runs its searches; if you turn on Windows' "indexing service," a search option normally left off, Microsoft's software can rip through a search almost as fast as Google's. The selling point here is more convenience and simplicity.

First, Google Desktop is quicker to launch than Windows' own file-search tool. Instead of opening the Start Menu to launch a separate program, you just double-click Google Desktop's icon in the bottom right corner of the screen to open its search page in your Web browser. Type your query and hit Enter, and the search results appear. And you don't have to choose between searching by files' names or their contents -- or even specify what kind of file to get -- since Google Desktop searches everything at once.

Second, Google Desktop eliminates the need to use the often slow and clumsy search tools built into Microsoft's Web, e-mail and Office software, the usual backstops to the Windows file-search utility -- for example, Outlook's "find" command, which by default looks through only the current mail folder, or Internet Explorer's history-search option, which scans only the titles and addresses of recently viewed pages, not their content.

The effect of this is to abolish that "where'd I put this?" confusion that regularly sends me through the "find" or "search" modes of my word processor, e-mail client and Web browser to locate the item that I had read in one program or another a few days ago.

If even Google Desktop can't locate the factoid you seek on your own hard drive, a click of a link in the Google Desktop window forwards the query to Google's Web search. Conversely, any time you run a search in Google's normal interface, you'll be presented with Google Desktop's search results automatically (these are added on your PC by the Desktop program, not by Google's own computers).

One thing to watch for, if you share a computer with other people: Google Desktop's searches will encompass everyone's data unless you adjust its preferences to exclude it from some folders or file types. Likewise, if you see Google Desktop running on a computer you're about to borrow, you'd be wise to click its taskbar icon (a rainbow-colored swirl) and select "pause indexing" to stop it from tracking your own use.

It can take a while to get used to leaning on Google Desktop as your first-resort file-finding tool, instead of whatever data-search options are built into the program you are using at the moment. Clicking over to a completely different program -- even though it's far faster, accurate and elegant -- can feel weird.

After trying Google Desktop for a week, I'm almost ready to make that leap. Why "almost"? Google Desktop needs to search through more than just the files created by Microsoft's own programs. To start, it must expand its Web and mail-search capabilities to such popular non-Microsoft applications as Mozilla Firefox and Thunderbird and Qualcomm's Eudora. It also ought to be able to index the contents of Portable Document Format and Rich Text Format files, plus instant-message chats carried out in non-AOL software.

But knowing how consistently Google has worked to improve its other services, I'm sure those changes are coming. Microsoft and Apple (which plans to introduce a search capability much like Google Desktop in next year's update to Mac OS X) should keep their notebooks handy.

Living with technology, or trying to? E-mail Rob Pegoraro at