Watch out for the W32/Sober-Z virus!
The Sober virus accounted for 42.9% of virus infections in November according to Sophos. It's a nasty virus that emails itself to all your contacts and then opens your pc to hackers. How can you avoid infecting your PC?
1) Run Anti-Virus software and keep it updated daily.
2) Get in the habit of not opening email attachments especially .zip, .exe or .scr files.
3) Switch to MacOS X. There are no viruses on the Mac.
More Info from Sophos:
Sophos virus analysis: W32/Sober-Z