Can't remove Nortel VPN eacfilt.sys

Can you advise how to really get rid of these Nortel VPN back doors while
still maintaining wireless connectivity to the Linkys home router?

I thought I removed Nortel VPN software on my home machine (a network of 1)
but when I installed a software firewall to bolster my Linksys wireless
router, I keep getting requests to connect to the software that I thought I
deleted.

NDIS Filter Intermediate Driver (eacfilt.sys)
has recieve a packet from the remote machine [192.168.0.1]
Do you want to allow this protocol driver to access the network?

NDIS Filter Intermediate Driver (eacfilt.sys)
is trying to connect to [192.168.0.1]
using remote port 53 (DOMAIN - Domain Name Server).
Do you want to allow this program to access the network?

NDIS User mode I/O Driver (ndisio.sys) has received a
Multicast packet from the remote machine [192.168.0.1].
Do you want to allow this program to access the network?

I tried saying "No" to these requests but then the wireless networking on the
Windows XP SP2 machine doesn't work. I tried deleting these two files but
again, wireless networking would not work afterward.
C:\WINDOWS\system32\drivers\eacfilt.sys
C:\WINDOWS\system32\eacfilt.dll

I thought I deleted the Nortel Contivity VPN Client as I had never used it but
apparently some vestige is laying around, for example.
C:\Program Files\InstallShield Installation
Information\{big number}
Service = test

I don't have another system to test whether these are "normal" messages but
they seem like a weak link opening the machine to hackers.

Can you advise how to really get rid of these Nortel VPN back doors while
still maintaining wireless connectivity to the Linkys home router?