Set up a mail account in Outlook and set it as the default mail client in
control panel, intenet options, programs. You can delete the mail account
from OE if you like.
You need to setup your mail account(s) in OL2003 and in OE go to Tools,
Options and at the bottom of the General tab unselect Make Outlook Express
my default mail handler. In OL2003 you can go to File, Import/Export and
select Import Internet Mail and Address and then select Outlook Express to
transfer your address book.