Unfortunately Windows chaos rules supreme
Applications may be installed either for a specific user or for all users,
and on XP that results in their configuration data files being held somewhere in
C:\Documents and Settings\{username}\...
or
C:\Documents and Settings\All Users\...
on Windows 7 it seems to be
C:\Documents and Settings\{username}\Application Data
or
C:\Users\{username}\AppData\Roaming
or possibly
C:\Users\{username}\AppData\Local
As I already indicated, you have to define %PROGRAMDATA% (or %ALLUSERSPROFILE%) if you want to use them under XP.
I guess that Piriform MAY have defined them as part of the environment under which CCleaner is running,
in which case the hopefully will work when you specify them as part of an INCLUDE or in a WinApp?.ini script,
but they will not exist for other applications under XP.
It took a long time but now I can stipulate %USERPROFILE% as part of an INCLUDE and it works for XP and W7.
For a very long time this has ALWAYS been a variable AVAILABLE to all applications under XP and W7,
but only recently does it work for INCLUDE.
Perhaps there is still Work In Progress.