The best way to keep on top of virus threats is to be vigilant about updating your software with bug fixes and security patches and regularly updating your virus definition files. However, if you want more information on the most current threats, you might try resources such as CNET's Security Center, McAfee's Recent Threats page, and TrendMicro's Top 10 Security Threats page.

http://www.cnet.com/2001-11351_1-0.html
http://us.mcafee.com/virusInfo/default.asp
http://www.techsoup.org/learningcenter/internet/page5261.cfm