Microsofts homepage about IT-security in the home, please read it! It is good stuff for free!

Sophos Anti-Rootkit, Free!

Webfilter for parents, K9 web protection, Free!

McAfee Security HQ

Symantec Security Response

CSI (Computer Security Institute)

The wildlist

CERT

SITIC (Swedish National "CERT")

SANS

SC Magazine

Säkerhet & Sekretess (In Swedish)

Hacking Exposed Tools

Linux Security.com