Nothing has changed in Outlook 2003.
Both of these methods work the same.
Why can't you use your Outlook Address Book?
The option for "New Message to Contact" after selecting multiple Contacts is
in the Actions menu.

Signature
Russ Valentine
[MVP-Outlook]
>I want to send one email to multiple contacts that aren't in a distribution
> list. In previous versions of Outlook, I could click the "To:" button of
[quoted text clipped - 7 lines]
> Message to Contact" but that's not an option when multiple contacts are
> selected. Thanks!