If you have an old Windows XP or Windows 7 laptop lying around, installing a legitimate copy of Office 2003 on that specific machine is fine for offline writing. However, for the sake of security, do not connect that machine to the internet.
Most search results for "Microsoft Office 2003 portable download" lead to:
Recommendation: Use LibreOffice Portable or SoftMaker FreeOffice Portable instead. They run better on modern Windows 10/11, receive security updates, and handle .doc/.xls/.ppt files reliably.
Forget co-authoring. Office 2003 has no cloud awareness. You cannot see your colleague typing in the same document. You are back to the dark ages of "final_v2_actual.doc" emailed back and forth.
You must be honest about the "work better" claim. In three critical areas, the portable dinosaur fails catastrophically:
