I create an appointment in Zimbra for November 10th 9 am.

In Outlook, it shows up as being at 10 am.

What am I doing wrong?

Outlook timezone is (GMT -5:00 Eastern Time) with adjust for Daylight Savings Time checked off.

This happens both from a Zimbra client in Mac OS X -- Eastern / US timezone and a Zimbra Client in Win XP SP2 -- Eastern timezone, both running Firefox 1.5.7.