My first job was an ISP I co-founded. Our first dial-up system was a classic 120MHz Pentium w/128MB RAM and 4GB harddrive, that served as the terminal server for 16 phone lines and let users start SLIP/PPP or a shell connection. It was not unusual to have 16 users logged into it at once running applications on it.
It also was our main e-mail server and web server, hosting both our own website and several customer websites. We had a second one of the same specs for a few other things and backups, but that was our main workhorse.
[EDIT: They were running Linux 1.0 and 1.2, first with NCSA httpd, then Apache; when we first got them they ran Slackware, installed from floppies; I think we ended up installing Redhat at some point before we retired them; the modems were hanging off Cyclades serial cards; and they were literally hanging - for our first 16 lines we had US Robotics Sportster modems hanging on the wall. (I'm writing this in the hope someone will tell me to get off their lawn and tell me how they did more with less, btw.) ]
It also was our main e-mail server and web server, hosting both our own website and several customer websites. We had a second one of the same specs for a few other things and backups, but that was our main workhorse.
[EDIT: They were running Linux 1.0 and 1.2, first with NCSA httpd, then Apache; when we first got them they ran Slackware, installed from floppies; I think we ended up installing Redhat at some point before we retired them; the modems were hanging off Cyclades serial cards; and they were literally hanging - for our first 16 lines we had US Robotics Sportster modems hanging on the wall. (I'm writing this in the hope someone will tell me to get off their lawn and tell me how they did more with less, btw.) ]