First, I just checked my SMB.conf for interfaces and 
found it commented that portion out (see below). Would 
that be why it's not showing up in testparm?:

#### Networking ####

# The specific set of interfaces / networks to bind to
# This can be either the interface name or an IP address/
# netmask;
# interface names are normally preferred
;   interfaces = 127.0.0.0/8 eth0

# Only bind to the named interfaces and/or networks; you 
# must use the
# 'interfaces' option above to use this.
# It is recommended that you enable this feature if your 
# Samba machine is
# not protected by a firewall or is a firewall itself.  
# However, this
# option cannot handle dynamic or non-broadcast interfaces
# correctly.
;   bind interfaces only = yes
------------

I also got the output of "ifconfig" (below) - p2p1 
being the active interface. I'm guessing the interfaces 
line above needs to be changed, but to what exactly?

Another piece of info that might help with answers is a
bit of info on the layout of my network...
any wired machines, access points etc are on the
192.168.1.nnn range
192.168.0.nnn wirelessly connected devices

lo �� �� �� ��Link encap:Local Loopback ��
�� �� �� �� �� inet addr:127.0.0.1 ��Mask:255.0.0.0
�� �� �� �� �� inet6 addr: ::1/128 Scope:Host
�� �� �� �� �� UP LOOPBACK RUNNING ��MTU:65536 ��Metric:1

p2p1 �� �� ��Link encap:Ethernet ��HWaddr 74:d4:35:be:72:6d ��
�� �� �� �� �� inet addr:192.168.1.200 ��Bcast:192.168.1.255 ��
�� �� �� �� �� Mask:255.255.255.0
�� �� �� �� �� inet6 addr: fe80::76d4:35ff:febe:726d/64 
�� �� �� �� �� Scope:Link
�� �� �� �� �� UP BROADCAST RUNNING MULTICAST ��MTU:1500 ��
�� �� �� �� �� Metric:1