Download Tiny Personal Firewall
Tiny Personal Firewall is a very complete software that allows you to protect your computer from malicious hackers or suspicious behavior of programs in your computer that may start automatically without you noticing.
Tiny Personal Firewall helps you to protect you operating system, it monitors Windows kernel components as well as hard drives and internal information. The software do this by monitoring any kind of traffic that surfs through your computer and detecting any irregularity in the behavior of your system.
You can download the trial version that last 30 days and buy it if you like its performance. You wont regret it.
Its compatible with Windows XP and 2000