To support Window Vista in my game, I have changed were the save files are placed (From under Program Files to My Documents) for both XP and Vista installations.

Now I would like to be able to move the current XP users save games from the old location to the new location.

I think I can correctly trigger this via the upgrade checking code like so:

<Upgrade Id="PLACE-GUID-HERE">
  <UpgradeVersion OnlyDetect="yes" Minimum="$(var.ProductVersion)" IncludeMinimum="no" Property="NEWERVERSIONDETECTED" />
  <UpgradeVersion OnlyDetect="no" Minimum="1.1.0" IncludeMinimum="yes" Maximum="$(var.ProductVersion)" IncludeMaximum="no" Property="OLDERVERSIONBEINGUPGRADED" />
  <UpgradeVersion OnlyDetect="no" Maximum="1.1.0" IncludeMaximum="no" Property="MOVESAVEFILESUPGRADED" />
</Upgrade>

where 1.0.x was the old way and 1.1.x will be the new way, thus I could do something in a custom action based on MOVESAVEFILESUPGRADED, but the heart of the problem, I cant see how to move non-installed files from one location to another.