I know this comment is late. The contribution is just in the interest of knowledge. The following is from Ramesh's site [Windows Firewall options are grayed out. Available: http://windowsxp.mvps.org/resetfwpol.htm. Accessed: 2007-11-27]:
Problem: Windows Firewall displays "For your security, some setting are controlled by group policy."
Resolution:
Method 1 - For Windows XP Home and Professional Editions
1. Start > Run > Regedit.exe
2. Navigate to HKEY_LOCAL_MACHINE \ SOFTWARE \ Policies \ Microsoft \ WindowsFirewall
3. Backup the key and then delete the WindowsFirewall branch.
4. Close Regedit and restart Windows.
Method 2 - For Windows XP Profession
1. Start > Run > Gpedit.msc
2. In Compuer Configuration > Administrative Templates > Network > Network Connections > Windows Firewall > Standard Profile,
set state of the 14 entries prefixed with "Windows Firewall:" to "Not configured"
3. Exit the Group Policy Editor.