other tables to consider are w3t_PollVotes, w3t_Favorites, w3t_Calendar, w3t_Boards, w3t_AddressBook will need to basically update any table that utilizes the U_Number field in any way from user #6 to user #2.
Donate to UBBDev today to help aid in Operational, Server and Script Maintenance, and Development costs.
Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.