I actually have never had to deal with office 2003 in a professional capacity, so I could not tell you. From what I remember the word processor always worked, it was Outlook that did not work eventually. After end of life they don't add new auth methods to the old software. Running Office 2013 and Outlook 2021 side by side was a disaster.

Is that office 2003 works on my system? Or Office 2003 at 3 different customers with an endless variety of hardware and OS combinations, mostly works?