Well a laptop won't give you the best results during gaming - you'll have to spend more to get a powerful laptop than you might on a desktop.
Also, it's never a great idea to build a whole computer, or decide your full needs based around 1 game. One day you might wake up and realise you don't want to play that 1 game anymore, and then you'll be stuck because your PC will be totally configured around that game, and may not be powerful enough to allow you to fully take advantage of other games.
World of Warcraft isn't that challenging on systems, so you can play it on pretty much anything. However WoW is pretty CPU taxing (as it's built on an older engine which doesn't make as much use of the GPU as current engines do.)
If you got a laptop for WoW, you'd really want a mouse if you ever got competitive. I wouldn't allow someone in my arena or raid teams if they weren't playing tip top, and I've never played WoW with anyone not using a mouse, even if they played on laptop. I'm sure it can be done, but it'll be more challenging for you, and may affect your performance in game.
I still think a laptop is a bad idea for gaming (you could get so much more by building your own desktop) but if you are set on it you could consider Alienware.
Aliewnware are pretty damn expensive (I tend to warn people away from Alienware because I think it's so overpriced) but I know very little about laptops, so you'll have to excuse my ignorance as to where to direct you. You could visit a company like Cyberpower.com or Arbico.co.uk and get them to build a laptop for you, which would probably work out cheaper than going to Alienware.
atm i can t perform at 25 man content, my fps fluctuates like from 40 to 10- 6...., even when i m not in raid. screen just frozes for few seconds. i mention that all game settings are to minimum. i ll be content if they were at least settled to a point , but never happens , always fluctuates.
2 - Run virus, malware and spyware scans (Microsoft Security Essentials is a good choice if you're unsure what to use)
3 - Defragment your drives.
4 - Download HW Monitor and find out what temperatures your GPU and CPU are reaching. If any of your CPU cores are above 70c then you may have a problem, and equally if your GPU goes above 75c then I advise you sort out some additional cooling.
If your PC is too hot, a lot of performance related issues (such as FPS drops) can occur.
If your PC is consistently too hot (for long periods of time or sporadically over time) then you can incur permanent hardware damage, which will drastically reduce performance and cause strange things to happen during intensive periods.
Hope that helps a little.
However if you want maximum settings you'll likely need a new system.