I have received a number of these emails which look like then have been sent from Microsoft, they have not.
Please do not click on any attached file as you will install trojans/spyware onto your computer.
If you have Internet Security any malicious attachments should have been removed.
!!! DO NOT OPEN ANY ATTACHMENT ON THIS EMAIL !!!
There is a genuine update from Microsoft called KB910721 and if you click on the picture above you will see it is for Exchange not Outlook or Outlook Express