I did also already considered using Wine. But more than likely this program won't ever have Wine at it's disposal in the first place.
I'm thinking about using the CurrentVersion key. Do the values
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemRoot
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\CurrentVersion
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\CSDVersion
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\RegisteredOwner
etc., exist on Vista and 7?