Email Battles has posted a list of free anti-viruts tools for Windows NT 4.0 Server

Although Microsoft has moved on, the world is full of Windows NT 4.0 servers, still chugging along. Problem is, many are chugging along due to budget constraints, which often means they are running without any protection from trojans, worms and other malware. Email Battles melded the best freeware anti-virus projects that run on NT 4.0 servers into one coordinated toolkit that, so far, has evaded NT's infamous Blue Screen of Death.

Legacy Fix: Marry Free Utilities for NT4 Server Anti-Virus Bliss