found this on the klm website:
Can I bring my laptop computer on a KLM flight?
It is possible to bring your own laptop.
Use of a laptop is permitted during the flight when the 'Fasten seat belt' sign is switched off, i.e. not during take-off and landing periods. The laptop also has to be switched off when requested by the crew. For power supply, you will not need an adapter and both 2- or 3-pin plugs can be used.
Services to accommodate laptop computers are offered for passengers seated in World Business Class on our Boeing 777, Airbus A330 and the Boeing Business Jet. KLM is planning to gradually introduce power supply for laptop computers in World Business Class on Boeing 747 and MD11 aircraft as from 2007.
Have a nice trip.
life is too short to drink bad wine