Thanks for the answer. It is (unfortunately) the answer I expected.
I am using the Windows bridge with the WIN32-TAP virtual adapter. It is
used to hook a variety of 'virtual environments' that run on top of Windows
XP to windows networks, including: colinux, openvpn and pearpc, so
unfortunately a third party consumer router is not an option in this
scenario. A networking solution with Mac layer filtering within the Windows
environments is what is needed.
Anyway, thank you again for your answer.
/Ross