My MacBook Air is light to the point that whenever I use it on a non-level surface (like my lap) or perched on the edge of something (like a table), the entire

My MacBook Air is light to the point that whenever I use it on a non-level surface (like my lap) or perched on the edge of something (like a table), the entire computer bobs up and down and moves around as I type. Heavier laptops by definition do not have this problem to a similar extent. The other problem with the weight is that if someone brushes past and snags something (a bag strap, clothing) on the display, I get really nervous that the entire laptop will go flying. With my 15" MBP, I'm just worried about the hinge breaking, or maybe if the surface is slick enough, the laptop sliding around. The Air has changed the way I use laptops and makes a noticeable difference in the weight of my purse every day, but some days it gets pretty nerve-wracking...