Fernie, are you sure the worm is actually coming from you, rather than from a spoof of your email address?
Hotmail, Yahoo and other web based email addies don't usually have the ability to send out spontaneous emails (unless hackers have gotten around this, which they could have).
It sounds more likely that someone who has you in their address book has the worm, and it's using your addy as a spoof. You could ask for full headers from somene who's received an email which appears to be from you, and see if you can trace it back to the originating source.
Barring that, as yeehaw said, are you also running Outlook on your computer?
Cheers,
Morgan