To be honest, I've never found a "laptop cooler" to work that well, so I am not really sure if it's worth it or not, to purchase one. In the future I'd like to acquire a variety of cooling devices to see if any really help, but that won't be for a while due to time constraints.
The problem is, a lot of coolers have fans, and rarely are fans located at the exact same spot on each laptop, which makes it difficult to purchase a cooler that's designed for your specific laptop. I forget who it is, but one company has these mats that dissipate heat quicker, but I forget who it is. That might be the best bet though.
I bought the Vantec Lapcool 4 with USB hub after reading numerous positive reviews of it.
(It's better than the Lapcool 5)
After using it, I noticed the keyboard is never warm anymore.
The fans are not too loud even at max, and playing CS:S, and WoW with the highest settings cause absolutely NO problems. I can play hours and hours with no problems whatsoever.
It also lifts the back of the laptop a little, which I believe helps with the ventilation as well.
I definitely love this product and recommend it to anyone whose laptops are overheating.