Getting this laptop with 8970m crossfire, what additional cooling will I need? I upgraded to the IC diamond thermal compound, I will get a notebook cooler...anything else? Don't want this thing to overheat..
You don't need anything else. Just mind your temps by using software when you are gaming or putting heavy load on the system. Also, keep the laptop elevated by roughly 1" - 1½" (which the laptop cooler will do anyway); this will allow adequate airflow. Don't allow the ventilation to become obstructed!
As far as maintenance, just blow out the vents every month or two. If you use the laptop on a daily basis, you should probably open it up to thoroughly clean the fans. It will also need new thermal compound about 6 months to a year into use, and thankfully with Sager notebooks, you can open up the system without voiding the warranty (or you can send it to them and have them repaste your CPU + GPU while you're under warranty).