Noob seeking 'Gaming Laptop'

Hi guys,

I have just recently been thinking about upgrading my desktop pc for a decent spec for gaming. I have no knowledge about computers what so ever so I need all the help I can get really. BUT now I am looking into getting a decent gaming laptop. I have been looking around and what have caught my eye are the Alienware laptops but of course they are well out of my budget. I will be using the laptop for gaming only and using my desktop for work etc...

I’m not sure what info I need to give for all you who can help me out because like I said I have no knowledge.

What I can do is give you a list of games that I enjoy playing, and hopefully we can start looking at different laptops.

Any additional information that will help me out about understanding what does what and why I need then please let me know  

Games:
World of Warcraft
Call of Duty 4: Modern Warfare 2
Mass affect 1 & 2
Dragon origins
Left for Dead 2

With the laptop I would like to keep the settings the games play in rather than reduce the quality.

Hope you can help me out

Regards
Clartymarty