Thanks again to all who have replied. I've included my smb.conf file for Dundas, for what it's worth.
Here's where I'm at after following all your excellent suggestions. When my iptables firewall is down I can ping my XP Home computer (TREVOR1) from the Linux computer (Linuxhost) and vice versa. When the iptables firewall is up and running I can ping the XP computer from the Linux computer but not vice versa. When the firewall is running I can see the Linux shares on the XP computer, but I cannot access them (makes sense); when the firewall is down I can both see them and access them. I can see one other computer (CATHY1 - Windows 95) on my LAN from the Linux computer, but I cannot see the XP Home computer to which the printer is attached.
There is clearly a firewall issue blocking access from TREVOR1 to Linuxhost. I am using a very simple firewall I copied from Fedora Linux for Dummies repeated below. These are the lines I added to iptables to make my firewall. Can anyone see where the problem is?
iptables --policy INPUT DROP
iptables --policy OUTPUT DROP
iptables --policy FORWARD DROP
iptables -A OUTPUT -o ACCEPT -j lo
iptables -A INPUT -i ACCEPT -j lo
iptables -A OUTPUT -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT
iptables -A INPUT -m state --state RELATED, ESTABLISHED
As for my inability to "see" TREVOR1 from Linuxhost, is that due to the fact XP Home cannot join a domain (I'm not exactly sure what that means in practical terms)?
This is not a big deal because I have been able to successfully connect my printer to Linuxhost as a local printer (long cable!), so being able to access it via the network is a matter of convenience, not necessity.
For Dundas, here's my present smb.conf file:
[global]
# workgroup = NT-Domain-Name or Workgroup-Name
workgroup = Owen office
username map = /etc/samba/smbusers
netbios name = localhost
guest ok = yes
encrypt passwords = yes
comment = Linux PC
server string = Samba Server
printcap name = /etc/printcap
load printers = yes
; printing = cups
; cups options = raw
; guest account = pcguest
; guest ok = yes
; log file = /var/log/samba/smbd.log
; max log size = 50
security = share
#
# You may wish to use password encryption. Please read
# ENCRYPTION.txt, Win95.txt and WinNT.txt in the Samba documentation.
# Do not enable this option unless you have read those documents
encrypt passwords = yes
smb passwd file = /etc/samba/smbpasswd
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
; local master = no
; domain master = yes
# Windows Internet Name Serving Support Section:
# WINS Support - Tells the NMBD component of Samba to enable it's WINS Server
; wins support = yes
# WINS Server - Tells the NMBD components of Samba to be a WINS Client
# Note: Samba can be either a WINS Server, or a WINS Client, but NOT both
wins server = w.x.y.z
# WINS Proxy - Tells Samba to answer name resolution queries on
# behalf of a non WINS capable client, for this to work there must be
# at least one WINS Server on the network. The default is NO.
; wins proxy = yes
[homes]
comment = Home Directories
browseable = yes
writable = yes
[trevor's data]
comment = trevor's home folder
path = /home/trevor
writeable = yes
browseable = yes
read only = no
Thanks for all the wonderful help I've received so far.

Trevor