The advent of Vista and Mac OS X, along with the ascension of Linux, add new dimensions to a long-time controversy. Now more than ever before, the Mac OS is the most cost effective operating system of all.

Think the argument in this article is a load of hooey? Believe that it's the most accurate examination of the Mac in the enterprise? Be sure to read the other viewpoint in Seven Reasons to Think Twice About Macs in the Enterprise.

The debate over the financial advantages of various OSes first sparked around 15 years ago, when the Gartner Group industry analyst firm came up with the concept of total cost of ownership (TCO). Since then, a number of other theoretical models have also been coined to weigh the business pros and cons of various OSes.

In 1999, for instance, Gistics released a landmark report analyzing Macs and PCs in terms of return on investment (ROI). Gistics' study was limited strictly to the publishing, graphics and new media fields. Among many other findings, the authors concluded that Mac creative professionals were producing $26,000 more each in annual revenues for their employers than their Windows counterparts.

Some six years later, soon after the advent of OS X, computer security expert Winn Schwartau created a widely publicized tool geared to helping companies in any industry measure the TCO of Macs versus Windows PCs. Schwartau emphasizes that results from the tool can vary considerably from one business to the next. But at his own small enterprise—then known as Interpact and now dubbed The Security Awareness Company—three-year TCO turned out to be twice as high for Windows than Mac.

Whether or not they've undertaken formal TCO or ROI studies, many customers today claim to be attaining substantial economic advantages from using Mac OS, either instead of or in conjunction with other OSes.

In contrast to the largely server-based Linux OS, Mac remains an operationally viable choice for widespread use on servers and desktops alike. And despite all the energy Microsoft has poured into the new Vista, Mac is still king of the hill when it comes to desktop ease of use—translating, at the end of the day, into higher productivity and lower tech support and training expenditures.

In OS X, Apple has innovated with an underlying Unix kernel for better security and less costly management on large networks. But Mac OS continues to run only on Apple's own well-engineered PCs, attested to by many enterprises and other business as more crash-resistant, reliable and long-lasting than other PC hardware. Furthermore, Mac OS continues to require fewer patches than Windows, for easier and less pricey maintenance.

Meanwhile, some industry analysts predict that Apple will garner new business out of Microsoft's Vista from longtime Windows customers who are unenthusiastic over the lack of driver support and other costly aches and pains of Vista migration.

Here are the details on a few of the myriad reasons why Mac OS is the way to go, financially speaking.

Macs bring a better overall value proposition

OK. You can buy a very low-end Windows-based PC for less than $300, if you know where to look. Good luck trying to find a Mac anywhere near that range. Even a Mac Mini will probably run you around $500.

But most enterprises are unlikely to buy ultra-cheap PC hardware anyway, points out Michael Gartenberg, an analyst at JupiterMedia. "Generally, businesses are not looking strictly at the most budget-minded hardware. They're interested in things like reliability, build quality, manageability and overall value. And from that perspective, Macs deliver very well," he says.

In Gartenberg's opinion, Mac machines compare favorably in pricing to similarly outfitted Windows-enabled systems from OEMs such as Dell, Hewlett-Packard and Lenovo.