Last year I was working on a project to install some new Cisco ACS servers at the company I was at. During the installation I ran into a problem that I had never run into with Windows 2000.
The issue that I ran into was not found in the installation guide so I thought I would outline it here for anyone else that runs into them.
Getting to the Admin Webpage
In order to configure ACS you have to get into the admin web page which is managed by the CSAdmin service. Once you complete the installation the service is automatically started and an icon is put on the desktop that points to http://127.0.0.1:2002. The problem is that if you pull up that icon straight after installing Windows 2003 Server and ACS, it will just come up with a blank page. The first reason for that is that you don't have the Sun Java Runtime Environment (JRE) installed. The webpage uses java to run and Cisco tested ACS (4.1 at least) with JRE 1.4.2_04 which you can download here:
Once you have installed the JRE, you have one more step to complete before you can launch the webpage (or you will still just get a blank page when you try and bring it up - with no warnings btw) which is to add the site to the "Trusted Sites" in Internet Explorer. You do this by navigating to Tools -> Internet Options -> Security and then click on the Trusted Sites Icon and click the "Sites" button. Here you will need to add "http://127.0.0.1" and click "Add". You will need to uncheck the "Require server verification (https://) for all sites in this zone" button because the ACS Admin page doesn't use SSL.
Once you have added the admin webpage to the Trusted Sites you should be able to just refresh the page and configure the application.