The video card is the most important thing in the video gaming laptop, for the video card determines how high of settings you can have on a game.

http://www.notebookcheck.net/Comparison-of-Laptop-Graphics-Cards.130.0.html

This website compares the speeds on the graphic cards, click on the graphic card that you are interested in, and notice the little list of models on the right hand border (it starts with Class 1 Geforce GTX 580) the higher the card is on the list the faster the card will perform. Sometimes they even compare it to other cards saying it is X% faster or -X% faster.

--------------------------------------

Now if I were to recommend specific models I am particular on ASUS for gaming laptops specifically their G7X series or the G5X series (X being a number for generation, the 15 inch versions will be much cheaper than the 17 inch versions.) Asus make well built gaming laptops with good ventilation (gaming laptops often overheat), and most models give a 2 year warranty, with 1 incident of accidental during the 1 year if you register the product within 60 days. I wouldn't bother on a gaming refurbished laptop.

Details here
http://completewarranty.asus.com/Content/US/ADW/adw.aspx

Note you will not get this accidental warranty if you buy from certain stores such as Best Buy, Office Depot, Staples, Costco and the Microsoft store

--------------------------------------

Don't bother with spending more money on more memory, anything 4gbs or more is plenty. Furthermore memory is cheap so if you ever want more you can always upgrade. Note if you upgrade prior to the warranty ending, you void the warranty once you open the case (which you will have to do to upgrade the memory).

--------------------------------------

While the processor does matter somewhat for gaming the graphic card is 5x as important. Anything with an i5 or i7 will be plenty. Note that the i5 dual cores are almost the same speed in gaming as the i7 dual cores and the i7 quad cores with only 3 digits in the number (such as i7 720qm or i7 740qm.) The i7 with 4 digits in the name are much better than the i7s with 3 digits in the name. This is because they are using the newer architecture of intels processors, which is faster for the same clock speed. Furthermore the i7 with 3 digits in the name were kinda intel's first attempt at quad cores with turbo boost so turbo boost didn't really work that well with them.

For example the i7 720qm could operate as follows
1.73 ghz quad core or 1.73 ghz tri core or 2.4 ghz dual core or 2.8 ghz single core.
So a standard i5 could often beat the i7 720 in games for many games can't use more than 2 cpus and almost all the i5s were 2.4 ghz or faster.

The new sandybridge i7 2630 is as follows
2 ghz normal quad or it can boost to
2.6 ghz quad, 2.7 ghz tri, 2.8 ghz dual, 2.9 ghz single. And the sandybridge i7 2630 is about 10 to 20% faster for the same clock speed compared to the i7 7xx generation.

Edit: Fixed a minor spelling error