This handy little application is designed to protect users' DSL or cable-connected PC from hackers. This edition of Zone Alarm includes four security services: a firewall, an application control, an Internet lock, and zones. All told, these four services allow users to control which traffic enters their computer and afford individuals the ability to monitor all activity on their computer as well. Finally, this edition also adds a host-file lock feature, effectively preventing host-file tampering. Zone Alarm 4.5.538 is compatible with all systems running Windows 98 and higher.