Apple's new war on Microsoft. Since Steve Jobs's return to Apple in the late 1990s, the company he co-founded has survived -- even prospered -- under sort of a Pax Microsoftia. Bill Gates invested some of Microsoft's spare change in Apple, and Apple made Microsoft's Internet Explorer the default browser on its Macintoshes.

Far more important, Apple did everything it could to ensure the success of Microsoft Office, the Mac version of which costs an obscene $499, or a considerably more reasonable $199 for new-Mac buyers. Apple's competing product, AppleWorks, was included free of charge only on Apple's consumer-market Macs; buyers of Macs aimed at professionals would have to shell out an additional $79. Moreover, there is no easy, seamless way of sharing files between the AppleWorks and Office worlds, as my irritated editors would be the first to tell you.

Now Jobs has apparently decided to go to war against Microsoft. Yesterday's new-product announcements, at MacWorld in San Francisco, are just the latest sign that David wants to compete head-to-head with Goliath. Last year, for instance, Apple unveiled its quirky and effective "Switch" ads in an attempt to get Windows users to come over to Apple. Of course, Apple has always depended on people preferring the Mac operating system to Windows, but there is a snarky "Windows sucks" tone to the "Switch" ads that belie the two companies' supposed alliance.

Also, the Mac enthusiast site Think Secret reported in October that the next version of AppleWorks -- which could be unveiled any day now -- was aiming for "[f]ull compatibility with Microsoft Office." Since compatibility is one of the few reasons anyone would shell out for the cumbersome Office, the ability to share files hassle-free would amount to a huge disincentive for buying Office.

Thus, the real interest in yesterday's announcement was not the two new PowerBook laptops, cool though they may be. It was that Apple will soon replace Internet Explorer as the default browser with a new browser of its own, called Safari, which is supposed to run three times faster than IE -- and that Apple will also market a $99 presentation program called Keynote that will compete directly with Microsoft's ubiquitous PowerPoint, one of Office's components.

Will it work? San Jose Mercury News technology columnist Dan Gillmor is skeptical but intrigued, writing that if Apple really intends to go after Microsoft, "it means more competition. That's healthier all around."

Apple obviously has a difficult road. With something like five percent of the market share, it needs to cater to the needs of customers who live in a Microsoft-dominated world. Who cares how great Keynote might be, for example, if its files are incompatible with those of PowerPoint? Yet unless Apple maintains its edge as a technologically superior alternative, it really has no reason to exist.

That's why I use Apple products, but invest in Microsoft. I don't see any reason to rethink either decision.