I have found the main cut-off for older machines is the early 2000's for easy painless install and functionality....
I"m not saying it's not possible to run a linux distro with a GUI on computers older than that I'm saying it's not fun to get them working and then there is the waiting for everything to load........
the distros that run WITHOUT a GUI actually have the ability to run on almost anything.........
anyone that uses computers today would be horrified by the routinely dropped connection, the slow to load semi-functional web pages and even connecting with dial up and listening for the tones to see if it connected right..
What we know as the "internet" was the grandson of the ARPANET and the classified MILNET which was essentially a fax service with a text message service built in but it could ONLY be used when no one was on the phone and if somone picked up the phone they got a high pitched series of tones squealing in their ears until the computer at the server side recognized a lost connection.
The internet was also limited to the private sector and military for government documents, warrants between the police and assorted three letter agencies, investigations across states or even internationally and was partially the reason for the laying of the under-sea cables in the late 50's and 60's.
in the early 90's the public started paying for the internet around the same price as cable tv today with around 100 times more fan fair like it was going to be the next step in civilization.........and in a sense it kinda was.....
but the internet was largely a confusing mess of hand typed HTML and HTTP protocols largely invented by a guy named Tim Berners Lee and a few friends that litterally gave their creation to the world for free so it was easier to communicate and share information with researchers near by and eventually the world.
the public was allowed an endless mess of search engines in their infancy with varied levels of usefulness, endless forums on everything from house care to foot fetishes with photos but videos were too expensive and took DAYS to download or upload and in many cases you couldn't watch the video online.
here is a demonstration using original hardware put together for your horror <link>
</link>
Just so you know it was common to take 10-15 minutes to completely "boot up" and you had to listen to all the beeps and assorted noises to know if your computer was working properly and THEN came the fun of dial up......
As an added fun fact officially the FIRST email was sent in 1961 from the Royal Palace of England to the USA that said
"Hello World"
- Queen Elizabeth
