Hello Dave. NEWT does require WMI, but also requires remote registry access. For machines on any workgroup, NEWT 1.0 requires you have default access to the remote machine. In other words, the remote user must be logged in as the same username/password you're logged in with. If you can open the remote registry and browse to the following registry path, NEWT should be able to scan that machine:
"HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall"
If you are asked for a username/password and you're able to get access after typing it in, please let me know. In that case I would suggest us sending you the latest 2.0 version. It has the ability to use custom usernames/passwords, for each machine if needed as well as many other improvements. We could email you with the info to the address you signed up with on the forums if you'd like.
You mention you've tried installing NEWT on one of the problem machines and running it from there. Are you saying you can't scan one of these machines locally when NEWT is installed on that very machine? If so there could be a few different reasons, but one could be that the logged in user for that machine doesn't have administrator rights to his or her own workstation. I also assume these are all NT-based machines? (NT4, W2K, XP)