Pictures in e-mail stationary

[Dodo]

I have Outlook 2007 on Vista and Outlook 2003 on WinXP SP2. Exchange 2003
SBS. All latest patches applied.
If I create a signature in Outlook 2007 and insert a JPEG either hosted on
the web (linked) or local, picture is displayed by receiver OK.
If I create a signature in Outlook 2003 and insert a JPEG either hosted on
the web (linked) or local, picture is NOT displayed on local machine or on
receiver's e-mail.

Thanks in advance for your help!