Do not go gentle into that good night,
Old age should burn and rave at close of day.
Rage, rage against the dying of the light.

-- "Do not go gentle into that good night," by Dylan Thomas, 1951.

It's just another day for Microsoft (NASDAQ:MSFT). The stock was trading sideways this afternoon, neither helping nor hurting the Dow Jones Industrial Average (DJINDICES:^DJI) The blue-chip index wwas also taking it easy, trading up by a modest 0.2%. Nothing to see here. Move along.

Except, it's also the end of an era.

Today is the last day of official support of the game-changing Windows XP operating system. The final Patch Tuesday plugs a critical security hole in Microsoft's treatment of Rich Text Format files, fixes another exploitable security flaw in some versions of Internet Explorer, and keeps abreast with the latest anti-hacking updates for newer Windows versions.

And that's it. Windows XP had a fantastic run between Oct. 25, 2001, and today. That's 4,548 days of user-friendly success, making customers forget about the atrocious Windows ME and the unpolished Windows 98. XP overshadowed its anointed heir, Windows Vista, and is still more popular than the latest and greatest Windows 8 platform.

And therein lies the rub. Microsoft has failed to move its massive user base over to newer Windows versions. Windows 7 is crushing XP in the open market, but even that replacement only holds 50% of the global desktop market. XP has faded slowly but still owns a sizable 28% market chunk. The two Windows 8 versions only add up to 11.3%.

Microsoft has pleaded with its customers, offered big discounts for moving up to a Windows 8 computer, and issued dire warnings about running XP without fresh security updates. But at the same time, Redmond pushed the totally redesigned Windows 8 platform way too hard, forcing an unfamiliar experience to replace the user interface used since Windows 95.

What sets Windows 7 apart from the far less successful Windows 8 is that it mostly works like an XP system would. The desktop environment feels familiar, the start button does its job, and everything is designed to accept input from a mouse and keyboard combo.

Fare thee well, Windows XP. We hardly new ye. Image source: Microsoft.

It's cool to come up with a better mousetrap, but Microsoft tried to unify its platform too quickly. Windows 8 assumes that you have a touchscreen and want to use it for everything, with keyboard and mouse support more of an afterthought. That's fine for tablets but unwieldy for full-fledged desktop and laptop systems.

Consumers (and corporate information technology shops faced with retraining entire workforces) balked at Windows 8, still prefer Windows 7 over the newer version, and will be sad to see XP go.

New Microsoft CEO Satya Nadella seems to understand these customer dynamics in a way that predecessor Steve Ballmer never did. Unfortunately, he took the reins in Redmond too late to make a difference to this particular paradigm shift. Preparing the old XP market for a wholesale change would have required years of careful planning and gradual design shifts -- not ramming Windows 8's touch-focused experience down customer throats.

So this is it. Windows XP is an unsupported orphan. Deep-pocketed customers can still pay millions of dollars for one more year of security patches, but these fixes won't be made available to the public. For most of us, taking an XP computer online will be like walking on the high-wire without a safety net. The next critical security flaw will go unplugged, exposing XP users to all sorts of ugly risks. And it's fair to assume that the most dangerous hackers and crackers might have saved their best dry powder for this very day -- why publish an exploit just before Microsoft stops fighting back instead of right after?

MSFT Chart

MSFT data by YCharts.

Microsoft shares have gained a scant 27% since Windows XP was released, trailing far behind the Dow's 72% run. It's been a long series of fumbles and false starts, and the company is sort of left without an heir to the XP throne.

This was supposed to be a catalyst for Windows 8 installations, but that never happened. Nadella had better put the pedal to the metal and come up with a more user-friendly design for the next Windows update. If not, Microsoft will simply chase faithful XP users off of the desktop and onto tablets -- or to less confusing desktop environments from other companies.