Microsoft WILL NOT email you security updates!
Just a word of warning about an ongoing virus attack via email.
The Swen, W32/Swen@MM, Gibe, and W32/Gibe-F strain of virus often arrives in an email masquerading as a security update from Microsoft. As the title of this post says, Microsoft will never distribute a security update in this fashion. All updates are downloaded directly via http://windowsupdate.microsoft.com.
This virus can exploit an old bug in Windows that allows it to execute itself, so please be sure you have all necessary updates from Microsoft. It would be embarrassing to be infected by something that was fixed 2 years ago. (SMILE)
If you get such an email, it is a virus or other hoax.