I don't think the problem is samba, since even with the server off
(all the way off. Cold.) the Windows workstations give a "Network is
not accessible. You might not have permission to use this network
resource" error when I try to View Workgroup Computers.

I'm not really sure how to troubleshoot this. I tried turning off the
AVG firewall that is running, but that didn't have an impact. At one
point the workstations *could* see the samba server, but couldn't
write to it. Then I changed some settings in my smb.conf (I am kicking
myself for not taking better notes on those changes) and suddenly I
can't even access the workgroups.

Any ideas?