Hide icon in taskbar for security purposes

I have an icon that displays on an XPsp3 machine for remote hosting. I want
to hide the icon from all users. I know that under a users a account, I can
go to the taskbar properties, choose customize, and then "Hide Always" this
icon. But, that only affects the one user. Is there a registry setting I
can use to hide for all users, or a policy in policy editor? Currently, I
have policies set so users cannot change the taskbar properties, but don't
know of any other policies?
Thanks.