i found (somewhere) that the information is stored in
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Streams\Desktop\TaskbarWinXP
there is a way to export this to the default user registry settings, but i cannot remember the steps right now.
also, the information is not stored in the registry when you setup the taskbars. once they are set, you need to reboot, then the registry key will contain the proper information.
this applies to winXPsp3.