For me its Dell D seriesD505 600 etc , in fact Dell produces the most rugged laptops
Lenovo(former IBM PC division) makes the most standard durable everyday laptop. I did some crazy demos with Lenovo notebooks and still worked.It could hold up to 150lbs, that helps give the screen and additional layer of protection. Panasonic tough book is for customized environment and is very expensive. Check out Lenovo T/R/W series.