In October of 1986, I purchased my first home computer a Mac 512ke. No hard disk, a half-megabyte of RAM and not quite 8MHz of processor speed. The Mac operating system at that time System 3.2 could not multitask pre-emptively or even cooperatively. But at that time, it was still considered innovative, as it was the first mass-marketed operating system to feature a graphical user interface (GUI).
Microsoft joins the interface race. About that time, Microsoft, realizing the future of operating systems was, indeed, not going to be command-line, developed a graphical shell to reside atop DOS. Windows 1.0 was absolutely awful, and couldn't even tile the desktop windows of its on-screen environment. Version 2.0 could at least support applications like PageMaker, but was undistinguished. In 1990, with the release of version 3.0, finally looked remotely like a Mac and began to capture the business market. However, its most pioneering feature was the "General Protection Fault," a new way to crash a computer.
...And the race was on. Microsoft, with its immense marketing prowess and oppressive contractual licenses to CPU makers, easily dominated the market. Apple's Mac OS had a brief chance in the mid- to late-80s but, in missing its few golden opportunities, surrendered the market to Microsoft dominance.
The need to support more than one platform. Resource Systems began supporting customers who used the Mac OS but, eventually, mixed-platform offices make it both logical and wise to support Windows as well. With the advent of Windows95 in August of 1995, Microsoft finally released a product that, although still a kludge from the standpoint of interface design and workflow, could spar quite effectively with the MacOS which, at the time, was in the midst of high-level mismanagement and underperformance.
I have rested my primary work machines, at least for the time being, with relying on Mac OS release 9.2.2 and OS X 10.3.1. By virtue of Connectix Virtual PC (recently purchased by Microsoft) product, I also run Pentium virtual machines on my G4 MDD Mac, permitting to run the Windows OS and native Windows apps as needed.
A new millennium (not the product) brings two modern operating systems. Now that both Apple and Microsoft have released fully modernized, robust operating systems Windows2000® for Microsoft and the UNIX-based OS X for the Mac legacy reservations about these platforms are, in large part, gone. (I am withholding any endorsement of WindowsXP for the moments, having some reservations with their use of related technologies that are inconvenient to some users and potentially invasive of privacy for all users.)
Long-term, I believe OS X will be an incredible operating system (as of OSX 10.3 or Panther, it is maturing nicely, although with some metadata/app-binding issues), certainly for the publishing and related creative media industries. Business should also reconsider the Mac, as OSX promises the robustness and scalability that has long deterred mainstream business adopters (although they accepted Win9x despite its notorious lack of stability or robustness). Even the home user should not be afraid of it, although I would refrain from showing most consumers how to achieve "root" access to the system.
My only reservations with OS X are that, with all the robustness of its UNIX core, it has in so doing invited some of the vulnerability to hacking and viruses that the legacy Mac was largely immune to. Also, the legacy Mac OS was first and foremost the premier innovator with application binding: the type and creator code technique of instructing the OS which apps link with what documents is far-and-away superior to any extension-related approach common to other OSes.
Finally, the greatest promise of OS X is dependent on developers of killer apps: those who will bring native OS X versions of their market-leading products to this platform. That began happening in 2002 and by late 2003, with the release of Quark 6, significantly marked that maturation, at least in a traditional Mac stronghold, print publishing. (Quark's delays gave Adobe InDesign a chance to secure ground in that vertical market, and many claim it a better product. Certainly more seamless, working with its Adobe brethren.)