Your talking about the MS-Blaster worm - comes in to your computer via a hole in windows. Run windows update to patch it or go to microsofts site and download (and run) the patch. You dont get it via email.
Very prolific atm. I formatted a PC and installed a modem - didnt patch as I only needed it for a day before reformatting it. Connected to the internet via modem and got the virus within 10 minutes!
If you have it removal instructions and tools are available from
www.sarc.com (if you can connect for that long)