OK - Here is what I found.
First, if you created an install of Office 97 using Developer, then you can do it pretty easily.
First, you need to open the MSI/ISM file. In the general properties, you need to find the "UPGRADE CODE". Take this (And take note of the Version Number as well) code, and you can do the following:
1: On a clean machine, run Tuner and start the creation of a transform for Office 2000/XP (doesn't matter which vsn you are going to)
2: Once you are done creating the MST, you have to go to the upgrade table in the direct editor, and add the "UPGRADE CODE" guid and then make the min version the number that the version is of your ISM of Office 97 and then make the max version the higher version you see listed....here is the confusing part. If you created the Office97 with a version of 97, then you will have to change the version MAX in the "Upgrade" table to one higher (since this is a full upgrade) so changing it from 10.00.0000 to 98.00.0000 will work.
3: Build it, and then test on a PC that has a Developer Created Office 97 build on it.
THIS WILL UNINSTALL YOUR OLD MSI BUILD OF OFFICE97 AND INSTALL OFFICE XP CLEAN. YOU WILL ALSO NEED TO REBOOT.
If you have any questions, I can send you more detailed instructions, however this is pretty easy, it just sounds hard, trust me 🙂
William