I had to run NT4 on a 4100 in prod at my very first Internet startup job.

We also had a bunch of 1000 and 1000a's, and an AlphaStation running AltaVista firewall all on NT.

An ALR 6x6 (6* Pentium Pros) was faster for Windows than the fully loaded out AS4100 IIRC. Except that the 4100 supported more memory and PCI slots IIRC.