Part of the gotcha's in buying PC's is the software maintenance costs. Win95 and WinNT are both a little temperamental, but much better than Win3 or DOS. However, when you track costs of Software, PC's get more money out of users in quite a few ways.
Forced Upgrading (OS)
MS makes big leaps in the OS. Like jumping from Win3.1 to Win95, or Win95 to WinNT. In each of these jumps users usually have to upgrade all (or most) of their applications, and many System Upgrades require Hardware upgrades as well. So Wintel users are bombarded with System software upgrade costs, hardware upgrades, and Application software upgrades. Each of these requires time (and money) to upgrade - usually just to fix major problems with previous versions.
Microsoft now admits that all those times they were saying that Win3.1 was as good as a Mac was wrong - that it really wasn't. But now they are saying that "this time, they mean it", and that Win95 is as good as a Mac. Of course if you look in the comparison section of this site or elsewhere, you will see that statement is false as well, and MS will admit that when they come out with the next big system upgrade, and promise - "this time, they mean it". Actually, they are already doing this with Win98 -- it is supposed to add functions like browser integration (even better than the Mac has had for years), multiple monitor support, and lower maintenance costs -- so this time they *really* mean it -- and ignore the fact that Windows95 wasn't (just like Windows 3.1, 3.0, and all the others weren't).
That is how MS operates -- it gets people to constantly upgrade (every couple of years), and pay them $100-$200 a pop (or much more) for the privilege of having their flaws fixed.
If you look at System software (and how old of machines your new OS runs on), you learn that Apple is much better at keeping their system software running on older machines. It wasn't until just the other day (System 7.5.5 and System 7.6) that Apple stopped supporting hardware created before '87, while Win95 wont run on most hardware before around '91 (and '94 if you want it to run well). So you can leverage your Mac hardware investments for twice as long as the PC counterparts (if you so desire). This is a primary reason why schools like Macs so much better than PC's, they can keep older machine more up to date and leverage the software longer.
Forced Upgrading (Apps)
Application upgrades are also important. With each System Upgrade, users of PC's are often forced to upgrade their application software. Technically users can run some 16 bit App (Win3 apps) on Win95, but they take performance hits and lose many of the features that where the reasons they upgraded the system software in the first place. While Macs have had a 32 bit architecture since '87 (and technically since '84), and users are much much more likely to get automatic usage of new features (because the OS is designed better in the first place). An example of this is that many Mac Applications worked automatically on PowerPC's - even though they were never designed for that entire architecture. This is so extreme that some Applications written for the Mac in 1984 will still run today on PowerPC Macs -- while MS did an internal study on how many 16-bit Apps had some bugs (some failures) running under Win95 and they got an astounding 30%. (Macs probably had a 5% or less error rate when doing a much larger architectural leap from 68000 based Macs to PowerMacs). So each System Upgrade will be more likely to require an Application software upgrade for PC users.
Now not only do PC's users get software upgrade gotcha's, but also lots of hardware ones as well. For example -
So you can see that there are many hardware gotcha's in the PC world that first time buyers are not aware of. By the time they find out, it is usually too late. Most PC users aren't even aware of the fact that Mac users don't have to suffer through the same agony as they do -- so they just assume that "Windows is as good as a Mac".
If you buy windows, you will be forced to upgrade your software and hardware far more often than on the Mac. This is what contributes to all the studies concluding that Macs life-time costs are far less than PC's.