Thats right, they have accomadated the heat with their cooling solutions... Larger laptops than most (semi portable).
The 480 parts are "M" parts, for mobile eg. 480M - they are down clocked mobile versions of the gf100 (or whatever) chipsets.
Sager laptops are one of the best, if not, THE best gaming laptops in the biz. They're sick beasts.
Heres a reference of the 480M: http://www.notebookcheck.net/NVIDIA-GeForce-GTX-480M.30196.0.html