After being a longtime FS9-er, I finally bought a PC powerful enough to try being an FSX-er too.

The question regarding LOWW scenery is as follows:
I was using FT LOWW FS9 scenery since the day it was out.
When the version 2 was released I bought the FS9 upgrade at SimMarket.
Now I want to use the scenery in my newly installed FSX. To be able to use version 2 for FSX do I have to buy an upgrade for FSX? Or the full version? And if the earlier, then which serial number do I have to insert during install? The one from the original FS9 version 1?
Sorry if the questions seem stupid but I am not sure about it and wouldn't like to make a wrong purchase.
Thanks in advance for any assistance and have a nice evening!
All the best,
Rafal