I've had pretty good luck with the empower ports working on my flights. I bought the Targus model that has various 'tips' that allow you to use it with Compaq, IBM, Toshiba, etc... (and as I switched computers 3 times last year, that helped).

I use this mainly for watching DVD's or listening to CD's on the flight. I don't work much on the plane. Your battery will not last through one 2 hour DVD.