Hello crubio,
First, let's see if you really do have a problem with a "pirated" installation of Office. Running the genuine diagnostics utility below will tell us.
In order to recieve the best support, we request all users initially download and run the Genuine Diagnostics tool at this link http://go.microsoft.com/fwlink/?linkid=52012. Click the "Continue" button, click the "Copy" button, then paste the report into your post.
If it does turn out that your current installation of Office is nongenuine, the simple fix is to go to Control Panel>Add or Remove Programs and click on Microsoft Office, then click Uninstall. Restart the computer after it's done and you have successfully removed the pirated Office.
For great advice on all topics XP, visit http://www.annoyances.org/exec/forum/winxp