Gateway LapTop Power Supply

Hi:
We have a gateway laptop. The power supply label says it puts out AC to the laptop. Thus, we can assume the laptop itself does the rectifying, etc. to supply the internal electronics and keep the battery charged.
That said, is there much to be gained by getting a "car plug" power supply over just plugging the existing power supply into once of those cheap converters to 120 volts from "car power."

John Gilmer wrote:
  Quoted Text Here  
Swings and roundabouts.
Using a "Gateway" car plug power supply intended for this laptop reduces complications if a fault develops and the question of warranty repairs arises.
A 120v converter can be used to power other things, eg the replacement laptop during the 3 month legal battle, above.
One solution, in practice, may be more energy efficient than the other, depending on your choice of units. That scarcely matters in a car, but could do in a yacht.
One may be significantly less expensive than the other. So you could gain a few extra pounds by spending the difference on doughnuts.
-- Sue