In the midst of Microsoft reminding everyone that Windows XP’s doomsday is less than a month away, Apple quietly announced that Mac OS 10.6’s doomsday was sometime last year, and no more security updates would be forthcoming for Snow Leopard.

That led to this piece about why anyone would still want to run Snow Leopard. Well, there are reasons for it–and for that matter, there are reasons why they would want/need to step back to 10.5 (Leopard). I don’t disagree with that part at all, but I do disagree with the point at the end, where he says that if you want a computer that lasts a long time, you have to buy a Mac.

Let me remind you that Microsoft is sending out reminders to people that it’s time to migrate off an operating system that hasn’t been generally available on new consumer PCs since 2007.There are a lot of aged Windows XP computers out there. Granted, there were a great many really shoddy Windows XP computers built over the years as well, but, generally speaking, a $600 computer is a $600 computer, regardless of whose name happens to be stamped on it. There aren’t a lot of corners you have to cut to reach the $600 price point.

Especially if you buy a business-class PC, you can expect many years of service from it. The market is flooded with off-lease business PCs that are several years old but will last for however long you’re willing to keep changing out the hard drive. You can reasonably expect a hard drive to last 3-5 years, and I’ve seen plenty of business-class PCs survive past their 10th birthday. At that point, they aren’t especially useful, but they still work if you have a job they’re up for. I used a 450 MHz Dell Pentium II workstation as a web server from 2002-2011. The machine was probably built in 1998. I’ve been routinely getting 10 years out of business-class PCs for a long time.

Don’t get me wrong: Apple has always had a reputation for building durable machines, with a very small number of exceptions like the ill-fated Apple III. But Dell and HP know how to build a durable machine too. They just do it when the price point calls for it. And when the price point calls for a $179 machine, they cut the corners to make it there, and you get a machine that dies two months out of warranty. Believe it or not, Gateway knew how to build durable machines too, and only shifted to the cheap, low end of the market when they thought they could make more money there.

But back to the original question, of why someone would stay with an older version of the operating system: Sometimes the hardware you have won’t support something newer, and sometimes the software you have won’t either. This is especially true in the Mac world. Forward and backward compatibility tends to only last a few generations on a Mac. So if you have an older piece of software, there’s a limit to just how new of a computer you can run it on. The magic thing about 10.6 is that it’s the last version that could be tweaked to run PowerPC-based software, and 10.5 is the last version that ran on PowerPC-based Macs.

That’s a longstanding practice that extends far beyond just Macintoshes. Unfortunately, when the computer maker leaves that generation of hardware and operating system behind, though, the security flaws remain.