Starting with the March 2018 Windows 7 updates, security patches will only install on SSE2 or higher computing devices (i.e., the Pentium 4 was 1st PC to offer this).  This change only affects a small # of users on 15-20 year old legacy PCs

Microsoft unexpectedly drops Windows 7 support for some ancient CPUs. Believe it or not, some hardy souls are still running Windows 7 on PCs equipped with turn-of-the-century Pentium III CPUs. But the latest round of Windows 7 security patches won’t install on those devices.  Beginning with the March update, those cumulative Windows 7 patches won’t install on a Pentium III system.

In August 2000, nearly 18 years ago, Intel proudly showed off its newest CPU family, the Pentium 4.  The Pentium 4 does have other advantages over the Pentium III, analysts said. It packs an improved floating point unit and a new set of multimedia instructions, called SSE2, that allow the chip to process multimedia in parallel, thereby speeding performance.

The addition of support for Streaming SIMD Extensions 2 (SSE2) was a big deal at the time. It was a high-end feature in 2000, but by 2004 or so every mainstream processor supported this feature. The CPU in your more modern PC almost certainly supports a later version; the latest and greatest release is SSE 4.2.

The point is, if you’re running a PC today, in mid-2018, that doesn’t support SSE2, you should be charging admission to your computer museum. You probably upgraded it from Windows 98 to Windows XP and then to Windows 7, and you’ve been humming along for nearly two decades, which is impressive.  SSE2 support became a big deal in 2012, when Microsoft announced that it was one of three mandatory CPU features required for its new OS. Windows 10 has the same requirements.