Microsoft has published a few articles about the Blaster Worm

What You Should Know About the Blaster Worm
At 11:34 A.M. Pacific Time on August 11, Microsoft began investigating a worm reported by Microsoft Product Support Services (PSS). The worm commonly known as W32.Blaster.Worm and its variants exploit the vulnerability that was addressed by Microsoft Security Bulletin MS03-026. For the most up to date information on the Blaster Worm, please visit: http://www.microsoft.com/security/incident/blast.asp.

Virus notice: Microsoft never distributes software directly through email.
If you receive an e-mail that claims to contain software from Microsoft, do not run the attachment. The safest course of action is to delete the mail altogether. If you would like to take additional action, report the e-mail to the sender's Internet Service Provider. Most ISPs provide an "abuse" userid for this purpose. For the most up to date information, please visit:
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/policy/swdist.asp

Next steps for ongoing PC security:
How do you keep your computer safe on the Internet? Clearly, preventing an attack is better than cleaning up after one. For the three steps to improve the security of your PC, please visit: http://www.microsoft.com/security/articles/improving_pc_security.asp