What do I do about my laptop heating up so much it shuts down?

I have a pretty nice laptop, and I only use it for gaming. However I just recently bought the game Aion and now my laptop tends to overheat and shutdown in the middle of the game. My computer has the capability to run this game with the graphics all the way up, so thats how I do it. But now I found myself in a bind because I'm lookin at these really good laptop coolers, however the reviews say that overall they dont keep the temperature down that much and your just payin way to much (I will only get a decent aluminum cooler, no plastic ones) so, how do I fix this problem?