#TinyCore #Linux is stunning. Here it is running successfully on a 1999 Sony VAIO with a single 333Mhz Celeron processor and 128Mb RAM.
Getting it booted was no effort; burn a CDROM and boot from it. Setting up wireless networking using an ancient D-Link branded WiFi USB dongle was a different story, but I got it working in the end.
That's the #Dillo browser running in the foreground!
@fluidlogic there's kolibri OS too. No WiFi, but it has Ethernet, and very low requeriments https://kolibrios.org