My HP has never shut down due to heat, even during the hot Texas summer.
If yours has the same ventilation design as mine, with the fan's intake on the back left on the bottom and exhausts on the left and back side, the ideal cooling solution I've found is to place a fan on the right side of the laptop. I use a simple USB-powered fan. It also helps that I have a 12-cell battery for my laptop, which sticks out and props it up. Airflow from the fan flows over and under the laptop, providing cool air for the cpu fan to suck in and helping push the exhaust out.
I've noticed that putting my laptop on one of those cooling pad actually makes it hotter. Likely because of the many passive cooling vents on the bottom. Heat's literally being pushed back into the laptop. And yet, since the intake's on the bottom as well, getting a cooling pad that sucks instead of blows would also be bad, since it'd starve the cpu cooler of air...thus my fan on the side solution.