Given Microsoft Corp.'s storied reputation as an intimidating competitor, few companies dare risk its wrath.

Yet Apple Computer Inc., with the San Francisco Macworld announcements of two applications that directly challenge existing Microsoft offerings, appears to be picking an ill-conceived fight with the behemoth based in Redmond, Wash.

Apple's free Safari browser obviously is intended as a replacement to Internet Explorer, which has been the installed default browser on all Macs since 1997.

The second application, a $99 presentation program called Keynote, takes aim at the PowerPoint module of the Microsoft Office software suite.

From Apple CEO Steve Jobs' demonstration of Keynote during his speech at Macworld, its visual abilities far outclass those of PowerPoint. Where PowerPoint tends to present static slides of text and graphics, Keynote incorporates graphically fluid transitions, such as pieces of a chart sliding into place.

Another effect makes the transition between slides appear as though they're mounted on the faces of a three-dimensional cube.

But most audacious is Keynote's compatibility with PowerPoint: It can save in PowerPoint format, as well as open files created by PowerPoint.

As both Safari and Keynote are Mac-only, the threat to Microsoft is confined to Mac users. Such a threat, however, could diminish Microsoft's enthusiasm for its 145-employee Macintosh Business Unit, which develops the Mac versions of Office and Explorer.

This scenario long has been one of Apple's nightmares. The thinking goes that without a Mac version of Office -- which, by the way, is seamlessly compatible with the Windows version -- many Mac users who need the program would be forced to switch to a Windows PC.

For a company fighting to hang on to its sliver of the market -- figures from research company IDC released last week put Apple's U.S. market share at 3 percent -- the loss of a critical application like Office could be devastating, if not fatal.

Paradoxically, that's exactly why Apple needs its own alternatives to Microsoft's products. The company must detest looking over its shoulder at Microsoft, wondering every time a version of Office for the Mac is released if there ever will be another. (The Web site MacFixit reported last week that Microsoft told it that the company will release another version of Office for the Mac but declined to say when.)

Here is where a little history can be illuminating. Back in 1997, shortly after Jobs' return to the Apple, the company was struggling and needed to buy time to reorganize.

Microsoft made a five-year commitment to the Mac, as well as invested $150 million in Apple, but with one very long string attached: Apple had to change its default Web browser from Netscape Corp.'s Navigator to Internet Explorer.

Mac users were aghast when Jobs announced the deal during a Macworld Boston keynote with a huge, Big Brother-like image of Microsoft chairman Bill Gates projected on a screen behind him. Industry observers, however, applauded Microsoft's move as a vote of confidence in Apple, which it sorely needed.

The agreement served Microsoft's interests by hammering another nail in Netscape's coffin while propping up Windows' only viable competitor, the Mac, as a hedge against the U.S. Justice Department's antitrust investigation -- though Microsoft has never admitted to this motive.

Furthermore, Microsoft always has made a respectable profit from its Mac products, estimated to be in the hundreds of millions of dollars every year.

Interestingly, the agreement was used against Microsoft a year later in the government's antitrust trial in Washington. Top Apple executives testified that Microsoft threatened to drop the Mac version of Office unless Apple made the deal.

"Apple needed to ensure that Microsoft would continue to provide MS Office for Mac, or we were dead," Fred Anderson, Apple's chief financial officer, testified in U.S. District Court. "They were threatening to abandon the Mac."

When the five-year deal expired last summer, neither company expressed interest in renewing it. Pundits speculated then that Microsoft was planning to abandon the Mac.

Now, it appears the opposite is true.

Apple learned a harsh lesson in 1997: that Microsoft, thanks to Office, holds life-and-death power over the Mac. Now, in far better financial and organizational health than it was then, Apple has put itself on a daring Microsoft detoxification program.

Rob Enderle, a research fellow at the technology research company Giga Information Group Inc. in Cambridge, Mass., called Apple's current moves "unwise," as the withdrawal of Microsoft support for the Mac platform "removes a level of validation."

Enderle said Apple could be acting pre-emptively. If Apple suspects, for instance, that Microsoft is considering dropping support for the Mac anyway, it needs to be ready for when Microsoft drops the bomb.

Even so, he said Apple could have quietly prepared substitute programs like Safari without provoking Microsoft with a public release of the software.

The risk to Apple involves more than just whether Microsoft would stop producing Mac versions of Office and Explorer. Microsoft, for example, could try to sabotage Apple's QuickTime video technology by crafting subtle incompatibilities into its next version of Windows.

The recent case between Microsoft and Santa Clara, Calif.-based Sun Microsystems Inc. in federal court in Baltimore over Sun's Java technology illustrates how this might happen.

Instead of using a Sun-approved version of Java, a programming language that can run on any computer, Microsoft in 1997 implemented its own modified version that didn't meet Sun's specifications.

This week, the judge ordered Microsoft to use Sun's version of Java, but the confusion Microsoft sowed in the interim has hampered broader adoption of the language.

If Apple decides it can afford to take this risk, or finds some way to appease Microsoft, Keynote and Safari can be seen as two pieces of a grand design. But what about the rest of Office for the Mac?

Apple already has the Office mail and calendar program, Entourage, covered, though not by one piece of software. But the combination of Mail, the Address Book and iCal, particularly the way they integrate with one another, as well as with the Mac operating system, adds up to a capable replacement for Entourage.

Microsoft never developed a Mac version of Access, the database module in the Windows version of Office, ostensibly because Mac users prefer the FileMaker Pro products from Apple's subsidiary, FileMaker Inc.

That leaves Word and Excel.

Apple does have word-processor and spreadsheet programs in AppleWorks 6, but their basic feature sets are no match for Microsoft's offerings. Yet if Apple is serious about extricating itself from Microsoft's grasp, it already should be working on world-class substitutes to Word and Excel.

A first-rate office software package would do more for Apple than negate any future threats from Microsoft. Apple also could control how such software integrated with the Mac OS, as existing "iApps" like iTunes and iPhoto do.

Best of all, Apple would control the price and earn the profit. One of the persistently distressing aspects of Office for the Mac, even given that it is highly polished software, has been its steep $500 cost. (The current "Office Romance" promotion, valid until April 7, entitles buyers of new Macs to a $300 discount.)

AppleWorks 6, by comparison, costs $79 and is bundled free with new iMacs and iBooks.

Apple could release a "pro" version of AppleWorks that's on par with Office for the Mac, charging, say, $349 or $399. A "lite" version of the suite, with fewer features, could sell for $99 and still be bundled with new consumer Mac models.

Both versions would have one vital feature: total compatibility with Microsoft Office formats.

Apple also could sell the individual "pro" components separately, as Microsoft does, except at a lower cost, of course. This shouldn't be too difficult, considering that Word, Excel and PowerPoint for Mac OS X sell separately for $350 each. Keynote costs $99.

As for Microsoft, it could choose between updating Office and competing with "AppleWorks Pro" -- that's what I'm calling it -- or drop all software development for the Mac and transfer its Mac Business Unit employees to the Xbox division. It would be great if Microsoft stayed in the game, as the competition would drive both products to improve and innovate, but it wouldn't have nearly the impact it would have had in 1997.

As crazy as this made-in-Cupertino-office-suite theory may sound, Apple has made a habit in recent years of making unexpected strategic moves, such as launching a chain of retail stores and building a portable MP3 player.

Why not AppleWorks Pro?