Here is a great workaround for monitoring NT4.0 servers. This will allow you to monitor things such as CPU and Memory settings. It can be installed in under 5 minutes and works great. The instructions suggested a reboot, but I found that just stopping and restarting the SNMP service worked fine. Thanks to Wink for pointing me in this direction. The official directions follow:
To update the Host-Resources-MIB on Windows NT4 complete the following steps
1) Ensure that Service Pack 6a is installed
2) Ensure that the SNMP service is installed
3) Extract hostmib.dll and hostmib.mib to the Winnt\System32 folder
4) Extract the registry files to the desktop
5) Double click each registry file to import settings
6) Reboot the server
After the reboot is complete, log on to the Orion server and open the Orion
Locate a Windows NT4 machine, right-clcik and select Node Details. From here
click the rediscover button.
Next, click on List Resources and the CPU, Memory and Volumes should be
available to monitor.