Somebody earlier said "Windows XP"
In my place of work there is a PC which performs what the bean counters would call a vital "show stopping" job in our organisation that has a speed of 133MHz and runs Windows 3.11

The only time anyone dared touch it recently was when the CRT monitor filled with ten years' accumulation of dust and caught fire....
( Scaryduck LIKES EGG, Thu 4 Nov 2010, 15:47, 3 replies)

Cool
I miss starting Windows from MSDOS
( shinyshinyscalp less a man, more a way of life, Thu 4 Nov 2010, 15:56, closed)

Damn
that pre-dates our still-in-production-use-public-facing webserver running on NT4

Uptime in the years at the moment...
( chthonic, Thu 4 Nov 2010, 16:41, closed)

Legend has it that until not that long ago
some six or seven year in fact, the uplink Sky uses near Southampton was controlled by an old 3.11 box - and the backup was a series of identical 3.11 boxes sat alongside, in case the 'live' one went bang.
Think how much a black screen would cost Sky...would you trust that to 3.11 in the year 2004?
( Fathter Puddytat Kill Kill dat widdle boid is mine on, Thu 4 Nov 2010, 17:08, closed)