The subject matter varies in the attempt to get people to download the bad exe file.

Sample: "Virus Activity Detected!
Dear Customer,

Our robot has detected an abnormal activity from your IP adress
on sending e-mails. Probably it is connected with the last epidemic
of a worm which does not have official patches at the moment.

We recommend you to install this patch (< --- concealed link) to remove worm files
and stop email sending, otherwise your account will be blocked.

Postmaster"

SANS:   http://isc.sans.org/diary.html?storyid=3117

AusCERT:  http://www.auscert.org.au/render.html?it=7813