Not Quite Older Than Dirt
In 1991 I bought a 486 system. Alongside an Amiga 3000.
The original 486 system had 16 MB of RAM and a 512 MB hard drive. The CMOS battery drained years ago. One of the RAM modules on the ATI video card is flaky.
Along the way I replaced the 486 CPU with a Cyrix Cx5x86 hybrid.
Along the way I replaced the 512 MB drive, which still works, with a 20 GB drive. With Windows for Workgroups 3.11 (WFW) installed on the first partition, I installed Slackware 11.0 in another partition. GRUB controls the boot options.
Thankfully, Linux and GRUB are not designed to be installed in any specific partition.
The system still functions. Once a year I connect the box to exercise the electronic components. Perhaps too for some nominal nostalgia.
WFW still runs as snappily as in 1991. The WFW interface is just as fast or faster than some desktops running today. Slackware 11.0 is sluggish at best. Once upon a time I tried SliTaz. The Linux bottleneck is the 16 MB of RAM.
I have WFW installed on a Pentium I class system, which has a 400 MHz K6-III+ CPU installed and a maximum 256 MB of RAM. That system still works. The hardware is silent. WFW screams on this hardware. I bought this system about the end of 1997, meaning the computer is 19 years young.
My first adventures with home networking was connecting both computers with a cross-over cable and port-forwarding.
Both computers are older than many people using computers today.
Unlike the simpler days of dial-up, neither system is useful today for web browsing. Way too much web site bloat these days compared to when the computers were manufactured. Yet these computers remain usable as standalone office desktops. MS Office 6, WordPerfect for DOS 5.1, or FrameMaker 4 remain as usable today as 20 years ago. While I have not used Eudora in many years, the email client should still be fully functional.
I have a Windows 2000 virtual machine (VM) with FrameMaker 7. I used this system as late as 2011 for a technical writing project. I installed Cygwin to resolve project work flow challenges. I used VM shared folders to shuffle files and email updated documents. Last year (2015) I received an email from the original project supervisor asking me configuration questions about the project with respect to new work flows and new software.
I have a Windows NT4 VM to preserve some complex MS Word 97 documents. To this day LibreOffice Writer does not import the documents without some frowning. A small NT4 VM presents fewer headaches. Preserving the documents as-is is simpler.
Humans love new and shiny. Defining when technology is “old” is subjective. As the familiar adage reminds, beauty (functionality) remains in the eye of the beholder.