Can you ping the gateway 192.168.0.1? Yes
The plot thickens...
First, I (so I thought) took care of the master browser issue - added registry keys to this (Vista Business SP2) machine - isdomainmaster=true & maintainserverlist=yes. Also changed network type to private. Rebooted, ran NBTSTAT -n and it showed this machine as master browser. Still couldn't see the 321.
On a hunch, I went to the other PC on this network (XP), put the ip address shown in the router pages for the 321 into IE and Presto! I'm looking at the login page for the DNS-321. Went through the wizard, gave it a workgroup name of Alabaster and named the device DNS-321. Mapped the drive and the XP machine sees it/reads it/writes to it. BTW, the XP machine has the opposite registry keys - false and no.
I go to the Vista PC, reboot and run NBTSTAT - shows as Master Browser. I open Computer, click Map Network Drive and the DNS-321 shows up as an option. When I click on it, however, it tells me the network path cannot be found. I try using IE and going to the IP - nothing. Also, the Vista PC no longer shows master browser when I run NBTSTAT. So, the problem is obviously with this Vista PC, but I'm not sure what direction to go now.
Anymore thoughts welcomed...