How to restrict limited user from uninstalling specific program xp home?

I have recently purchased AVG Antivirus plus Firewall. Another family user of my computer, does not like AVG so uninstalls EVERY time he logs on and finds it.

I have tried just setting his account to limited, but this does not stop him from uninstalling.

I have noticed a few other posts regarding this subject, but need basic advice on what exactly i need to be doing to stop him running the uninstall, and also to restrict the user from bypassing my restriction, so to speak.

thanks in advance for your help.