Top 10 Computer Security Threats of 2004
Adware-180
Adware-Gator
Exploit-ByteVerify
Exploit-MhtRedir
JS/Noclose
W32/Bagle
W32/Mydoom
W32/Netsky
W32/Sasser
W32/Sdbot (family including sdbot, gaobot, polybot, spybot)


Notes:

Listed alphabetically. Includes both enterprise and consumer threats defined as:

1) spyware/adware threats
2) email-borne virus threats
3) malware threats delivered by spam.