True 1080p laptops are few and far between.
Most computer aspect ratios, laptops included, are 16:10 (there are new monitors out that are 16:9, but this is a new thing and most laptops haven't caught on). The resolution required for 1080p is 1920X1200, and you will always have some black bars for 1080p movies, but you will have full 1080p resolution.
You will probably (in most cases) need a 17" laptop screen to get this 1920X1200 resolution.