I believe he is talking about MS Outlook and not Outlook Express. At least, he only mentioned Outlook and not OE. Hmm, we'll see.
Outlook is seen in the Windows Server2003 and 2005 editions as far as I know. For XP and previous versions of Windows 9X-ME Outlook Express has been the main name. Vista sees Windows Mail with the Business and Enterprise editions being the possible exceptions there. Whether Outlook or OE the name change for Vista was the thing to note.