First, if it's asking for the CD, then you probably didn't install Office XP from an administrative installation. Second, you probably didn't install Office XP per-computer. I suggest that you take a look at the Microsoft Office XP Resource Kit for more information about creating administrative installations. In order to install Office XP per-computer, log on to the computer as an administrator, and then add ALLUSERS=2 to the Setup command line.
This was first published in May 2003