Installer Location changes based on UAC Status

[Edos]

Hello,

We want to force our users to install the application just for the specific user that install it.
To achive that we skip the screen that gives the user the option to install "for all users" (the default value is ALLUSERS=False) and we define it wo run asInvoker.
On Vista and Win7 when UAC is set to ON everything works fine (both the installer and our target dir are under C:\Users\<user name>\AppData\......).
On windows XP (that dont have UAC) the instllaer files are instlled under all users folder.
On Vista and Win7 when UAC is set to off/Never Notify the installer files are not instlled any more under the C:\Users\... branch but installed under c:\program data\...
Note that the target dir (the files of our application) is still respected and installed under the C:\Users.... branch

Any idea how we can make it work for XP and for UAC off?

Thanks
E.S