Virus in disguise
A virus/worm is making the rounds cleverly disguised as an e-mail from Microsoft, warning you that you need to apply the attached patch (!) The patch is, of course, the virus.
I got one of these this morning, and Norton nailed it for me. I have seen warnings on the internet about it as well.
The message is quite sophisticated. Links on it are real links. It's a fake.
Microsoft NEVER sends such e-mails.