Difference between DSLR body materials + dropping a camera?

Ive dropped both of mine many times (D90/plastic aluminum, and D200 alloyishesque) and they are both fine. My D90 once 8 feet down onto cement too once... I will say that nikons, pentaxes, and olympuses are tougher built than canons and sony's so that is a hard one to answer. I say it is durable however a friend dropped her 550d rebel and it was trashed as the innerds were damaged, mine however has never had a hiccup...