Opening email client and adding attachment...

I can successfully open up a user's default email client and create a
new email with this:

proc.Start("mailto:aaa@bbb.com?subject=Test)

But i need to add an attachment to the email. I know mailto does not
include an attachment argument. But is there any other way to add an
attachment?

The system.web.mail namespace can do emails with attachments, but i
need to open up a regular email client program like Outlook, or Eudora.

Possible?

Thanks,
John