^ "Regret it to this day T_T " I would not feel this way. There is a High chance that It may have prolong the demise of your laptop, but probably not by much.
Generally laptop coolers are not very effective. Buy design they only try to cool the bottom of the laptop, So If bottom does not get hot it will have almost NO effect.
1) Many laptops have a plastic Bottom which reduces the effectiveness.
2) Cooling is buy done by forced are cooling the bottom, However, inside the laptop you are relying then on convection (radiating) the cooler bottom as primary cooling is Moving air inside the laptop - O did someone say plastic is not a good conducter of heat (or inthis case cool). May be more effective if laptop bottom is metal.
3) Idealy, to cool the inside of the laptop you need to increase the air intake, so unless there are air intakes on the bottom of the laptop - you can only expect a couple of degrees cooler. For Laptops with vent holes on the bottom a Cooler is more effective.
4) Go to newegg and click on the one/two egg ratings.
Link to the most popular coolers.
http://www.newegg.com/Product/Product.aspx?Item=34-997-730&SortField=0&SummaryType=0&Pagesize=10&PurchaseMark=&SelectedRating=1&VideoOnlyMark=False&VendorMark=&IsFeedbackTab=true&Keywords=%28keywords%29&Page=2
http://www.newegg.com/Product/Product.aspx?Item=34-997-730&SortField=0&SummaryType=0&Pagesize=10&PurchaseMark=&SelectedRating=1&VideoOnlyMark=False&VendorMark=&IsFeedbackTab=true&Keywords=%28keywords%29&Page=2
For some they are very effective, ie bring down the Temps by about 10 C - which is great. But for these I suspect they have a fair amount of vent holes in the bottom.
Looking at the picture of the Bottom of the laptop the OP bought, there are limited vent holes. How effective a cooler would be, My quess 2->5 C cooler. %C may be worth it. The vents for Her's is like my i5-2510M Samung 17" w/540M GPU intake on the side.
What I would do before you buy, is to do two things.
1) Run the laptop for about an hour in game mode, check the bottom temp, if only mildly warm, probably not worth it. If Hot would recommend.
2) Run the game and Monitor The CPU core temperatures, if they are under 65 C you are OK. SB/IB CPUs decrease Speed around 95 C. If Hitting above 65C, I would try a cooler. To verify temps, use a program like CPU-z.
http://www.cpuid.com/softwares/cpu-z.html