Brian Caulfield, writing in Forbes magazine, asks who’s winning the battle between Microsoft and Google? The answer, according to him, is Apple.

Microsoft was originally condemned to be broken up after it was deemed to be a monopoly by a federal judge in November 1999. Bill Gates fought that off in November 2001 on appeal, agreeing to a settlement.

The deal blocked Microsoft from preventing rivals building applications to run on Windows. Steve Jobs has been using that ruling to make Apple a Windows software player ever since.

For starters, Apple can now do all sorts of things with its operating system that are off-limits for Microsoft. In January 2001, it introduced Apple iTunes, software for buying and managing multimedia content that is now baked into every Apple. In January 2003, it introduced a browser, dubbed Safari. In 2005, Apple released a version of its OS X operating system with a slick, built-in search feature dubbed Spotlight. “They’re the only company that actually forced Microsoft off of the operating system because of their integrated Safari browser,” says Rob Enderle, principal analyst at Enderle Group, referring to the latest version of Apple’s OS X software.

Better still, from Apple’s point of view, Microsoft has to keep its doors wide open to whatever Apple product Jobs cares to give away. That’s helped Apple’s iTunes software crush Microsoft’s alternative among users of the Windows operating system. “It’s like giving a glass of ice water to somebody in hell,” quipped Jobs at this month’s D: All Things Digital conference in Carlsbad, Calif.

For Apple, the trick is selling more hardware, not destroying Microsoft’s software monopoly. And Apple can give away its software because that’s not where it makes its money.

Microsoft seems to have jumped out of the frying pan into the fire.