I have a similar question and can't seem to figure out the solution.  (I'm
having trouble understanding the whole "View" concept).
I am using Outlook 2002 SP3.
I have identified 35 Categories that I'm using to classify my appointments
and contacts.  I have then figured out 10 groupings of these Categories so
that they could be color-coded on my Calendar.  (e.g., the Categories of
Contractors, Competitors and Planning would all fall in the Label of  
"Business" and be color-coded Blue).
When I schedule an event I'd like to only identify the Category and have
Outlook automatically apply the Label and color code on the calendar.
So... with the Calendar displayed in Day/Week/Month, I chose:
View---> Current View ---> Customize Current View ---> Automatic Formatting
I then added rules to set the "Name" to Business and "Label" to Business
with Label color of blue for the "Conditions" of Advanced - Field of
"Categories" contains Contractors and also criteria of "Categories"
containing Competitors or Planning.

When I click Ok, it seems to work and the appropriate events are
color-coded, but after doing a few other things in Outlook, the colors have
disappeared and the Automatic Formatting rules/criteria have disappeared as
well.

What should I be doing differently?
.....maybe there's an easier way...?