"Malicious attackers are once again taking advantage of event-based social engineering attacks, and are currently mass mailing fake notifications for Microsoft’s Patch Tuesday, attaching a copy of Trojan.Backdoor.Haxdoor, next to a legitimately looking PGP signature which is, of course, fake too :"
I guess this really doesn't need to be said: You never open an attachment to an email unless you know what it is. NOT what you think it is! Microsoft will NEVER send you an email about Microsoft Windows Updates.
The second Tuesday of the month is Microsoft Patch Tuesday, and if you don't have your computer set to get the patches for you or at least remind you they are ready for you to download and install. You should. Very few patches haven't worked as built. Some under special circumstance like an HP with an AMD CPU. HP uses the same build for all computers, when it has an AMD CPU they install more drivers and this has been known to cause issues. (Driver conflicts.)
So if you haven't done your Microsoft Windows updates this week, Do them!