Not sure if you plan to use the on-board power ports, but most of the Empower-style systems (and AA's system as well) only put out 70-75 watts. My laptop has a 14.1" screen and it is excellent for text, graphics and for watching DVDs as well (and it is nice to exit the plane with a fully-charged battery
Another option is to consider the greater resolution of an SXGA screen (rather than the "standard" XGA).