From the LockerGnome (http://www.lockergnome.com) newsletter:
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Office 97 Privacy Issues and Patches
http://officeupdate.microsoft.com/Articles/privacy.htm
This page includes: "Microsoft Office 97 Unique Identifier Patch; this patch, once applied will prevent the insertion of a unique identifier number in all new Office documents." and "Microsoft Office 97 Unique Identifier Removal Tool; this is a utility that can be used to remove the unique identifier from previously created Office 97 documents. Customers who are concerned about the presence of the unique identifier number can run the utility against one or several documents at a time."