Linux FT. From a magazine cover disk in around 1996. I was a teenage oik working at a company where I suggested setting up the Internet for email and support use. The manager at the time subscribed to bill Gates' belief that the Internet was a fad. I was granted an old 486 desktop pc, and modem and a basic modem account.
I setup a squid proxy and email server with dial on demand. It was slow but it worked.
I moved onto redhat 5 after (before it became the enterprise thing), we went to isdn and leased line and I even had a stack of usr courier modems under my desk by the end with dial in for both Internet and collecting mail (for sales mostly).
It only got replaced when the company actually paid for a full time IT manager (I was primarily a software developer, doing IT on the side) and they switched everything to windows.