Sorry I answered late, I was off the intarwebs yesterday.

Whenever there's CAD involved I tend to discourage laptops. The reason is the videocards; you need CAD videocards that have the required drivers, and AFAIK no laptops have these. (edit: d0zer covered this already)

i7 Quadcores do turboboost as well when needed, so you should be fine. 16GB RAM should be sweet, and since its corporate laptops, try to get some SSDs in there on corporate budget

You did get the Dell Precisions, right?