Try to be more specific about what you want in a laptop. Features, size, weight, battery life.
The most powerful notebook you can buy for gaming in that price range would be a 17" Clevo D901 based system such as the Sager NP9262 with a fast dual or quad core CPU and a 9800M GTX graphics card but you will sacrifice portability to some extent. The Sager 8660 is very nice for a 15" notebook and one of the most powerful for the price. There is a 15" Alienware with a faster 9800GT graphics card available which is the fastest notebook available currently in the 15" size range but it costs more.