Lets not forget the cause of the problem this could be an exploit “Incorrect MIME Header Can Cause IE to Execute E-mail Attachment” which was patched ages ago by MS:
http://www.microsoft.com/technet/security/bulletin/MS01-020.mspx

If your computer is not patched you will be liable to reinfection, don’t keep treating the symptoms, treat the cause.

Regular visits to windows update.