This morning our inbox's have been hit hard with the SoBig.F worm which attempts to spread itself via e-mail attachment as reported by The Inquirer. Now is a good time to stress that you should only open e-mail attachments that you are certain are not a virus or worm, otherwise delete it.
The virus installs a copy of itself in the Windows directory as a file called winppr32.exe, and then the registry is changed so that the worm executes at startup.More information @ The Inquirer
The file size, said iDefense, varies in order to attempt to thwart anti-viral software, and typically comes as an attachment with email subject headings such as Re: Details, Re: Approved, Re: Re: My details, Re: That movie, Re: Thank you!, Re: Your application, Re: Wicked screensaver, Thank you!, Your details. µ