The Price of Security

This three-part "free security suite" is touted by Consumer Reports as being "on a par" with the ones that will cost you, and better than last year's versions. 

(links to free downloads)

1. Avira - Antivirus Personal 

2. MS Windows Defender
(If you're running Vista, this is already included.)

3. Spamfighter Standard

Beats complaining about it.