So safe it doesn't work

The amazing combination of using ZoneAlarm to firewall, and Norton AntiVirus to scan in-coming POP3 mail on WinXP Home will definitely protect you from mail viruses - by not allowing outbound connections to your POP3 server. Whatever helper application or DLL Norton uses doesn't register with ZoneAlarm's list of user-approved applications mechanism. It did use to work with an earlier Norton and ZoneAlarm on Win98, where it was just dog slow.