Spencer,
as I have been running the 8100/80 as a web and FTP and Mail server (including 10 customer www sites and FTP upload/download for them) for three years let me tell you it is a great machine for this sort of task. I ran it under Mac OS 7.5.5 (Open Transport, of course) with 48 MB of RAM, 1.2 GB Quantum hard disk. WWW server was an older version of WebSTAR, Qualcomm EIMS as mail server.
This configuration has turned out to be very stable. I only had an ISDN-type leased line (64 k), but the 8100 will clearly take advantage of a T1 line, too. All the better for you if you have a better connection than I had....
Walter.