Griff heres the problem with some of those models.
ASUS N series is pretty much a thin and lite series. N56 comes with the GT 630M, at best you will be playing counter strike, maybe Bad Company 2 on medium. 96 to 144 shaders depending either way its a renamed Fermi core. That at best is equivalent to the 555M found in Razer's original Blade laptop which at 2500 dollars promised to be the worlds (first true) FAKEST* gaming laptop and let you play BF3 on low. The N53's 550M isn't going to impress either way your playing counter strike.
HP, out of the box just like the last 5 years they will NOT sell you any good graphics chips at any price and they already expect you to pay way more for lower end hardware than ANY other manufacturer. ZDV7 starts out GT 630M +125 to get the 650M putting us at 1,l24...eww. DV6 is the same deal.
Dell XPS 15, before even hitting the configurator, from dell's site this is going to be a BAAAAD deal. Have to hope to find a mass market version in a store somewhere at 1300 dollars for a i5 and GT 630M, dell continues to be a rip off. They literally always start off with low to mid range hardware and then double the price of what others are charging, its insane.
Lets skip on down to the Alienware M17x/M18x. The M17x R3 is a discontinued model, so your talking in store and used. But new the R4 At $1600 dollars you can get DUAL 670M's in SLi so at this price range I am scratching my head at these single GPU laptops. The 17 inch unlike what a glance at the main page might suggest starts out with the 7970M not the 680M which is 350 more already putting you 500 bucks ahead of any other 680M laptop I would be shopping. But lets look at the Radeon, appears to perform between the 675M and 680M as they are saying so no reason to change that out unless you REALLY hate AMD.
There is no way in hell the M18x (r1 or r2) is a Clevo P270. The Clevo P270 is a desktop cpu using behemoth. Unless you were putting it in the same category. But its a 15 pounds, dont use it on battery every way too big laptop.
Clevo W170ER is a mid ranger, 650M not upgradable. Sager NP3265 635M not upgradable which is a real nightmare for gaming. However say the Clevo P170EM would be something to desire.