Microsoft has also never provided a downloadable installer for Office 2003, aside from a 60-day trial version that has long since been discontinued. The company's official recommendation for users who legally own the product and need to install it on a computer without a CD drive is straightforward: copy the contents of the original installation CD to a USB drive and run the setup from there. This method creates a standard, installed version of Office on that specific computer—not a portable one.
It stores all configuration settings in its own folder instead of the Windows Registry. Microsoft Office 2003 - Portable Version full version
The portable version of Microsoft Office 2003 offers several advantages: Microsoft has also never provided a downloadable installer