I know that there were changes from 97 to 2000/XP that affect several areas. I had to rewrite a few macros because of the Object Library changing. The change here is that 97 used DAO, while 2000/XP use ADO.
Was the Excel upgrade the only change? Did you upgrade Operating System to XP? Have you gotten a new PC? Are you using MSQuery to import into Excel? I have upgraded Excel a couple times with few problems in my OBDC connections.
But an OS upgrade (especially to XP) can be a different story. In Windows XP if you don't have Administrator Privileges, that can set off a bunch of problems. Took me @ a week to resolve all the issues.