Disable Firewall via group policy

[geoff]

I want to prevent users from using / enabling the
internet connection firewall that ships with XP.

The following group policy on the local machines looks
like it should do the trick:
Local Computer Policy
Computer Configuration
Administrative Templates
Network
Network Connections
enable the following "Prohibit use of internet connection
firewall on your DNS domain"

The following explains what activating the above should do
"If you enable this setting, Internet Connection Firewall
cannot be enabled or configured by users (including
administrators), and the Internet Connection Firewall
service cannot run on the computer. The option to enable
the Internet Connection Firewall through the Advanced tab
is removed. In addition, the Internet Connection Firewall
is not enabled for remote access connections created
through the Make New Connection Wizard. The Network Setup
Wizard is disabled"
However it does not work. Reboot or not, you can still
enable the firewall on the advanced tab on the domain
network connection (or any dialup connections you may
have)use network wizard etc

Has anyone got any ideas how i can lock a machine down so
users can not enable the firewall easily?