gaming laptop is a myth i tried the xps and alienware both sucks and till now my alienware having loads of problems even its 1 month old so i guess the best option for a gaming get a DESKTOP because the laptop is 1 hour without plug in and it will get hot and stuff so take me as example
They're definitely not a myth. I owned a gaming laptop myself and it was a pretty good performer; one of the fastest computers I've ever used. It was also very cool and quiet; I ran this computer 24/7 for a while and would barely be able to tell it was on without viewing the lights. The battery life wasn't great (2-3 hours on average, an hour or less under heavy usage), but if you're really concerned about that, take a look at the NVidia Optimus/AMD Dynamic Switchable Graphics technologies. Dedicated GPUs in laptops are significant power drains, and these technologies aim to increase battery life by making use of the integrated GPU during times of low graphics usage (Youtube, office work, etc.).
If you're still thinking about a gaming laptop, here are a few things to look for:
Processor: Intel 2nd-Gen Core i5 minimum (i7 if you can afford it; the 1st-Gen Core i5s and i7s are also pretty good performers, but I believe they have higher power consumption. Don't quote me on that though.)
RAM: 4GB minimum (8GB is standard)
HD: 500GB minimum (standard size now; SSDs still aren't mature enough and too expensive so I wouldn't recommend those for now)
GPU: NVidia and AMD have been putting out some really good stuff lately, so either or is fine. For NVidia, GT500 series is preferred; AMD, HD6000M series (make sure it's dedicated for both brands)
Any other features you want are for you to decide; those are just what I think makes a decent gaming laptop.