Firewall
From Windowsxp
There are quite a few firewalls available for Windows XP. I consider Jetico Personal Firewall to be the best, however, it's rather complex. Several popular firewalls are reviewed below, with a preference toward free firewalls.
Jetico Personal Firewall v1
License: Free
Overall, my favorite firewall. Matousec.com rated it as a close second in its overall list of firewalls [1].