I helped several people over the last two weeks whose appointments were off by an hour or two. This is almost always the result of using the wrong time zone or daylight time setting. In each case, the users lived in an area that does not honor daylight saving time, but they used a time zone with the correct offset then unchecked the option to automatically adjust for DST.
While this may have worked fine in older versions of Windows and Outlook, when you use current versions and live in an area that does not honor DST, you need to select a time zone that does not support DST.
When each user switched to a time zone that did not have the DST checkbox, the appointment times were correct.
If you don’t live in a no-DST time zone, you might think this tip doesn’t apply to you, however, anyone who creates appointments in Outlook 2007 or Outlook 2010 and chooses different time zones when creating appointments or uses the dual time zone features needs to choose a time zone that has the same DST properties as the intended location.