On February 2nd 2007 Microsoft issued a new Security Advice notice - Microsoft Security Advisory (932553) (http://www.microsoft.com/technet/security/advisory/932553.mspx) - which, surprise surprise, is using MS Excel as the route to attack your computer. The following are known to be vulnerable
Office 2000
Office XP
Office 2003
Office 2004 for Mac
Office 2004 v. X for Mac
There is no patch for this as yet and the vulnerability may yet affect other Office products. Be wary of e-mail attachments downloaded Office files.
:?
See also:
http://www.symantec.com/enterprise/security_response/weblog/2007/01/watch_the_exploit_a_targeted_a.html