Here's the top20 virus threats according to Kaspersky:

Position Change in position Name Proactive Detection Flag Percentage

1. +5 Email-Worm.Win32.Bagle.gt Trojan.generic 28,05

2. +3 Email-Worm.Win32.NetSky.q Trojan.generic 24,01

3. +5 Email-Worm.Win32.NetSky.aa Trojan.generic 14,63

4. Email-Worm.Win32.NetSky.t Trojan.generic 4,75

5. Return Email-Worm.Win32.Bagle.gen Trojan.generic +Registry access 4,30

6. New! Trojan-Downloader.Win32.Small.dam Trojan.generic +Invader 3,07

7. +5 Email-Worm.Win32.NetSky.b Trojan.generic 2,56

8. New! Trojan-Downloader.Win32.Small.ciw Trojan.generic +Invader 2,23

9. -2 Net-Worm.Win32.Mytob.c Trojan.generic 1,99

10. Return Email-Worm.Win32.Mydoom.l Trojan.generic +Hidden Install 1,99

11. -1 Email-Worm.Win32.Scano.gen Trojan.generic 1,44

12. Return Email-Worm.Win32.NetSky.d Trojan.generic 1,43

13. New! Net-Worm.Win32.Mytob.bt Trojan.generic 1,24

14. Return Worm.Win32.Feebs.gen Hidden Data Sending 1,12

15. New! Trojan-Proxy.Win32.Lager.dp Trojan.generic +Invader 0,74

16. Return Email-Worm.Win32.Mydoom.m Trojan.generic 0,69

17. -2 Email-Worm.Win32.Warezov.do Trojan.generic +Registry access 0,68

18. Return Email-Worm.Win32.NetSky.y Trojan.generic 0,46

19. +1 Email-Worm.Win32.NetSky.x Trojan.generic 0,46

20. -3 Exploit.Win32.IMG-WMF.y Data Execution +Registry access 0,37

Other malicious programs 3,99

When Bagle.gt appeared in the Top Twenty for December 2006, the idea of an intensification of the struggle between virus writers to gain control of users' computers.
Why? The end of 2006 was important for the constant evolution of Warezov, another worm, which so far has more than 300 variants.

Warezov and Bagle are in direct competition with each other: they both gather databases containing email addresses, and make it possible to send spam trough the infected machines.
This type of business is extremely money-making, so the authors of Bagle could not dwindle to react to the appearance of a competitor.

In December Bagle.gt took the fifth place, and has since risen to the first place. It currently makes up nearly 30% of mail traffic, showing that it will probably continue to cause problems for Internet users for some time to come. Now at least, all Warezov variants are being dashed back by Bagle and other malicious programs.