In its September issue, Consumer Report rates anti-virus, anti-spyware, and anti-spam applications. Here's a summary:

Antispam:

Consumer Reports Recommended:

Allume Systems' SpamCatcher 4 (http://www.allume.com)
MailFrontier Desktop (http://www.mailfrontier.com)

Antispyware:

Consumer Reports Recommended:

Microsoft AntiSpyware
Webroot Spy Sweeper (http://www.webroot.com)
Computer Associates eTrust PestPatrol 2005 (http://www.pestpatrol.com)
Spybot Search & Destroy (http://www.spybot.info)
Ad-Aware SE Plus (http://www.lavasoft.de)

The first three get a "very good" detection rating, Spybot and Ad-Aware get a "good" rating.

Antivirus:

Consumer Reports Recommended:

Trend Micro PC-cillin Internet Security 2005
Kaspersky Labs Anti-Virus Personal 5.0
Symantec Norton 2005
Alwil Avast! Antivirus
McAfee ViruScan 2005 9.0