Good gaming Laptop?

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Ok so my computer that I use regularly plays games horribly. It literally can't play anything besides videos. So I was wondering if anyone could recommend a good gaming computer, that would also be good for surfing the web and watching video. I could also upgrade my RAM and graphics card on this, but I have no idea if it would work.

The only gaming computer that strikes my eye that is within my price range is the Alienware M11x Laptop. So before I go out saving for this, I just want everyones recommendation. Keep in mind it needs to be a Laptop and needs to be under $650 as that is my budget. Thanks in advance.

Also how much would it be too build the Laptop instead of buying it straight up.
Also my school is getting Macbooks next year and I want to know how good they run games before I go off buying an entirely new computer

EDIT: Can I get this thread moved to the Land Lubbers forum?