Protect your PC for free
Anti-virus software is a big business. But some software is available with fewer bells and whistles free of charge:
AVG Free Edition - will scan your computer and e-mail for bugs
K9 - Probability-based filtering software that will learn to recognize key words and phrases in spam and will also check your e-mail against DNS Blackhole Lists, which tracks spanner-only domain names.
Zone Labs ZoneAlarm - Worried about hackers using your PC for malicious deeds? ZoneAlarm is a firewall--it blocks outsiders and lets you control unwanted access from the Internet.