EDIT: After looking at benchmarks for a while, this is the best bang for $499, the
A10 ...
http://www.newegg.com/Product/Produc...82E16834256941
Here is a second, smaller model with the A10 CPU/7660G GPU combo -
http://www.newegg.com/Product/Produc...82E16834256880 - it is $50 more ... but if you don't want the big screen, then here's a small one.
It's a quad core, at 2.3GHz w/ 3.2GHz turbo; and has the better 7660G graphics. That has 384 shaders. 381 GFLOPS, Open CL 1.2 (so it can crunch), OpenGL 4.1 and DirectX 11.1 (gaming) w/ shader model 5.0.
Compare this to the Intel HD 4000, which is somewhere around 83 GFLOPS. In OpenCL computing it will roughly double the output of the HD 4000.
Now, the 4 CPU cores are still not going to be quite as powerful as a nice i5 with HyperThreading, but they should get close, and the GPU should crunch about 2x as fast as the best Intel GPU.
Last edit: The absolute best CPU you're going to get for $500-ish in a laptop is the Intel Core i5-3210M
. The price is directly comparable to the AMD A10-4600M units I listed above. The trade off with going Intel at this price point is certainly faster CPU cores, with the sacrifice of roughly half the GPU OpenCL crunching power.
A link to a good candidate is here: http://www.newegg.com/Product/Produc...82E16834230927
I guess in the end only you can decide if you want better CPU cores or better GPU, because that's the trade off at this price point.
Hope that helps, I'm done.