unable to home network Vista & XP using NetBEUI as only bound prot

I am trying to resolve a home networking issue between one Vista Business
laptop and several XP Pro SP2 & SP3 machines on my existing, functional
NetBEUI home network (File and Printer Sharing for Microsoft Networks &
Client for Microsoft Networks bound only to NetBEUI, not to TCP/IP -
additionally, NetBIOS over TCP/IP is Disabled - all machines).

I searched around here for 'NetBEUI' and didn't find much.
I realize that support for NetBEUI vis-a-vis Vista has been discontinued by
MS and have read MS KB articles about that. That doesn't necessarily mean it
cannot be done.

I've installed Link-Layer Topology Discovery (LLTD) protocol on the XP
Pro machines and can now see them in the Vista Network and Sharing Center
network map. I have also installed the NetBEUI protocol on the Vista machine
and have configured NetBEUI (bound) and TCP/IPv4 & v6 (unbound and NetBIOS
over TCP/IP Disabled) identical to the XP Pro machines.

However, I am unable to see the XP Pro machines in Vista Windows Explorer >
Network, only the Vista machine itself.
Conversely, I am unable to see the Vista machine from any of the XP Pro
machines - even when searching for it directly by it's computer name,
'P200-S03_VB'.

I have my existing Workgroup name correctly entered for the Vista machine.
I have Vista User Account Control turned Off.
The Vista Guest account is turned On.
In Vista Network and Sharing Center, my network type is Private.
Under Sharing and Discovery, I have:
Network discovery, File sharing & Public folder sharing (read only) turned On.
No printers are installed on the Vista machine.
Password protected sharing & Media sharing are turned Off.
I have my Vista's 'Downloads' folder shared with Read(ing) Allow(ed)
Permissions for Everyone (only).

I am using the ZoneAlarm (free) s/w firewall on all machines with all IP's
on my private subnet configured as 'Trusted', although, in the case of the
NetBEUI protocol, this is likely not relevant.

I should be able to network among all machines with the above parameters,
however, the only way I can establish network connectivity between all
machines is to bind File and Printer Sharing for Microsoft Networks & Client
for Microsoft
Networks to TCP/IP(v4, only, in the case of the Vista machine) and set
NetBIOS over TCP/IP to Default on all machines.

If anyone knows specifically why I can't (yet) network with NetBEUI, I'd be
very interested to know.

FYI - For the inevitable 'Why use NetBEUI?' questions, I prefer to use
NetBEUI because NetBEUI traffic cannot cross my router (or come in to my home
network) and by leaving TCP/IP unbound and NetBIOS over TCP/IP Disabled, my
home network security is significantly enhanced.