Below 17" this you have only the small 1366x768 resolution and 11"-16" screen size.
A nice one at 700$ is http/www.newegg.com/Product/Product.aspx?Item=N82E16834152277 It has a fast HDD, powerful video card and one USB3 port into a small size and medium weight laptop.
Maybe you can ask the following questions:
1. Do you want a desktop replacement or a light traveling notebook?
A desktop replacement can be heavy, with a big screen and powerful components.
A light notebook is light, smaller screen and weaker components.
2. What is the maximum amount of money that you can spend?
Because you asked for a $600 laptop and you also added the $900 Alienware M11x laptop.
3. Do you want USB3/HMDI/eSATA/PCMCIA or other special port?