Here's a quick and easy way to pull in the National Holidays from Outlook 2003.  

1) To first create the United States Holidays in Outlook 2003:
Pulldown tools, select Options,
click on Preferences tab,
click on Calendar Options button,
click on Add Holidays button,
select United States,
click OK.

2) Then to move those Holidays over to ACT:
Pulldown Tools, point to Outlook Activities,
select Update Activities,
select "One-Way from Outlook Calendar to ACT! Calendar",
select all of the current year as the date range,
click OK

We repeat this process every calendar year.