Get out of the Outlook trap

For everybody switching from Windows to Mac (or any other OS or even to another Windows Mail client), transferring mails (with attached files) from Outlook to Mail.app, Entourage or Thunderbird or whatever they like to use has always been difficult at least (yes, I did it several times).
The great Mac OS X Hints website had very usefull tip today wich could ease this pain a lot.