[Samba] smbstatus, SWAT, etc. not displaying NetBIOS name for XP SP2 machines

[BJ Quinn]

I'm trying to see what computer is accessing certain files through 
samba, and the SWAT status page is a useful tool for that.  Problem is 
that for some computers, only the IP address shows, not the NetBIOS 
name.  This is only a problem with certain computers.  Since we're using 
DHCP on many computers I don't always know off the top of my head what 
computer has any given IP address.  We're not using DNS or WINS, just 
good old NetBIOS resolution via broadcast or whatever.  I think I've 
narrowed down the troublemaking computers to 5 or 6 of our 40 computers 
and they all have one thing in common - they're XP service pack 2.  (Ok 
well one of them is a Fedora 4 box not running a samba service, so I'm 
not surprised.)  I've double checked that the XP boxes are set to 
"hybrid" for node type, I've given them static IPs, I've turned on the 
messaging service (apparently required in order for them to respond to 
certain types of nmb lookups), and nmblookup -A [ip address] does return 
the name of the computer from our samba server.  What am I doing wrong?  
If nmblookup can find the name of the computer based on the IP address, 
what is samba doing differently that it can't find the name of these 
computers?  Thanks in advance for the help!

-BJ Quinn