Activate your Firewall
There are two ways to activate your firewall with Windows XP. The most simple way to do it is to download it from the link http://www.tiscali.co.uk/help/nbfirewall.html
If you do not want to use this you can do it yourself by the following procedures
Go to your "Start" button and choose "Control Panel"
In your "Control Panel" open the option labeled "Network Connections"
With your mouse, right-click on the broadband connection to be able to choose "Properties"
Go to the "Advanced" tab and check the box labeled "Protect my computer and network by limiting or preventing access to this computer from the Internet"