I am on KLM/NWA's Airbus 330-300. Just to follow-up with what I learned, I was advised by the airline that the seats in the two-person rows on each side of the aircraft are NOT suitable for stowing pets. The window-seats have the entertainment systems under them, and the seat next to it (the aisle) is more narrow to accommodate for the legroom lost by the entertainment system in the window seat.

The only place one can sit on this plane with a pet is in the MIDDLE of the four-person row. There is no bar separating the legroom of those seats.

Hope this helps anyone else that might need it.