Acad 2008/2009 CUI File

Hi all
When starting Acad for the first time as a user, a copy of the acad.cui file
is placed in C:\Documents and Settings\\Application
Data\Autodesk\AutoCAD 2009\R17.2\enu\Support.
If you want to customise the cui file for all users, where should the
modified cui file be located as "the master" from which all future user
versions will be copied? (IYSWIM)
TIA
Phil