Quick and dirty method:
1. Use a table view to display all the data fields that you want to export to Excel, filtered to show just one category if you like.
2. Choose Edit | Select All.
3. Choose Edit | Copy.
4. Paste to Excel.
Use Excel to calculate the difference between start and end date/times and add up the total.

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I would like to be able to easily add up all the durations of all the
> appointments that meet a specific criteria such as all the appointments in a
[quoted text clipped - 4 lines]
> out but I am not familiar with what macro commands are available in Outlook
> and how to make the macro operate on only the appointments I want.