Well, this HP XW6000 Workstation was originally shipped with Windows 2000, and uses first-generation DDR RAM.
It has a pair of individual 2.4 GHz Xeon CPUs too, and if the power supply fails, I'll have to scrap the whole thing because nobody makes a replacement (though several manufacturers claim to) that will work with this motherboard.
The user's manual was printed in January of 2000.
I'm sure somebody's got an older beast still running.