Free Firewall Software

• ZoneAlarm Computers running Windows XP Service Pack 2 generally have an incoming firewall built in. However if you want to stop any application that's on your system from accessing the internet then you need a two way firewall. ZoneAlarm provide a free version of their firewall software for individual and not-for-profit charities. The link can be hard to find so click here to go right to it.
• Microsoft Windows Firewall Windows Firewall is available as part of Windows XP Service Pack 3. It is also part of Windows Vista. Download Windows XP Service Pack 3