I have just run the sfc /scannow command, just to see what the result would be.
If you've ported Windows Mail over from Vista like I have, then the scannow command returns the Windows Mail folders back to the default installation settings.
Windows Mail will no longer run.
I had to boot into Vista and copy the program files folder from Vista to Win 7 to re enable Windows Mail.
The Windows Mail program store in app data remains unchanged.