Both Windows and Linux are distinguished for their pathological conviction to never break userspace. Linux has its warts because of this, but since it&#x27;s 10 years younger than DOS and since, as a Unix kernel, it was always very clear what the kernel should and should not do, it doesn&#x27;t have quite the trail of hacks seen in Windows.<p>Windows has broken legacy programs though. In Windows 7 a lot of old programs stopped working in the consumer editions of the OS. I don&#x27;t know if they&#x27;ve continued making their &quot;professional&quot; editions that provide comparability. I suppose that&#x27;s a reasonable strategy to encourage developers to update their software without killing user productivity, which could workout for the best in the long run.