Fourteen years ago, Apple was teetering on the edge of bankruptcy, just months away from running out of cash and, more important, in danger of becoming irrelevant. Today, the company is a technology juggernaut thanks to modern products like iTunes, iPod, and iPhone, and will soon overtake Microsoft from a market cap perspective. But with this market power comes closer regulatory scrutiny. And this week it was revealed that the US Department of Justice (DOJ) has been quietly examining Apple's digital music market tactics, looking for antitrust abuses.

The DOJ inquiry, thus far, has involved interviewing key players in the music industry and Internet music markets. The agency is particularly interested in Apple's bullying of record companies: Apple has apparently punished various companies that provided rival Amazon.com with temporary music exclusives for its "MP3 Daily Deal." This punishment involves dropping all marketing efforts for those labels and artists on the dominant iTunes Store, Apple's online music service.

It's a serious issue: While iTunes represents less than 27 percent of all music sold today, it is the dominant online music store, representing about 70 percent of all music sold electronically. Amazon.com is a distant number two with just 8 percent market share.

The DOJ inquiry isn't the only regulatory scrutiny Apple faces. Separately, the Federal Trade Commission (FTC) is examining Apple's rules requiring developers to use only Apple tools if they wish to sell iPhone applications through Apple's online store. (The only legal way to distribute such apps to individuals.) Apple suddenly changed that rule when Adobe released a cross platform tool that would have enabled developers to more easily create iPhone apps.

Apple is also part of a wider probe into tech industry hiring practices. This probe involves Google, Intel, IBM, and other companies.

That Apple faces potential antitrust action now is not coincidental. While many still prefer to think of the company as a tiny upstart trying to change the world, Apple is in fact a gigantic, successful corporation. Long removed from flirting with bankruptcy, Apple is now a company to be feared, and it has proven far more ruthless, in many ways, than competitors like Microsoft and Google. Indeed, according to at least one financial measure, Apple is poised to surpass Microsoft as soon as this week.

That measure, market capitalization, or market cap, involves calculating the value of a corporation by multiplying its share price times the number of outstanding shares. Market cap is considered a "public consensus" of a company's worth because it focuses almost solely on the stock price, which isn't necessarily indicative of the overall worth of the business.

But boy, does it have Apple fanatics excited. This week, both Apple and Microsoft are worth about $220 billion from a market cap perspective, behind the biggest company on earth (again, from a market cap perspective), Exxon Mobile, which is worth $280 billion. (As a comparison, Google's market cap is "only" $151.43 billion.) But while Apple has been on an upwards trajectory for years, Microsoft has fallen, and big time.

The issue here, of course, is excitement. Apple makes big bets on new products, dropping old ones very quickly, and in effect behaving like a technology startup. Microsoft, meanwhile, is slow and plodding, because it serves far more customers and needs to ensure stability. One company offers shock and awe, and Wall Street responds. The other has a loyal customer base of over one billion users, and Wall Street yawns.

By various other measures, Microsoft continues to outperform Apple. It had higher revenues ($58.4 billion vs. $42.9 billion) last year, and much, much higher profits. (Microsoft's $14.6 billion in profits this past year are almost three times as high as Apple's $5.7 billion.) Microsoft has much more cash and cash-like assets on hand as well, $39.7 billion, vs. Apple's $23.1 billion. And Microsoft has continued to dominate Apple in its original, core market of PC sales. After years of high profile efforts and failed ad campaigns, the Mac still accounts for less than 4 percent of PC sales worldwide.

15 years ago, when Apple was slowly slipping away into irrelevance, Microsoft was seen as the tech industry bully, and it was becoming distracted by increasing antitrust scrutiny of its own. Indeed, Microsoft's antitrust troubles only very recently came to a close, not just in the US but in the EU and elsewhere. Today, the tech industry is, in many ways, very different. Microsoft is still huge and powerful, but it finds itself challenged not so much by small, web-based companies, like many expected, but rather by huge, powerful companies—Apple and Google—that don't behave like huge, powerful companies.

This new dynamic presents an interesting competitive landscape in which Microsoft is no longer the only tech superpower. And while this may be exciting, mostly to the Apple crazies, it's actually good news for all technology users. Microsoft does its best work when pressed by strong competitive challenges, and it has never faced stronger competitors than Apple or Google. No matter which company's products you prefer—I suspect for many people, it's actually a mix of all three—this epic battle will ultimately have just one winner: You.