VR Zone published some gaming benchmarks that compare the performance of the upcoming GeForce 9600 GT 512MB with some other NVIDIA and ATI graphics cards.
This video cards is supposed to be around $160 when come out, and it will compete with HD3850 256MB
It scores less in 3dmark than HD3850 512MB but it performs better in gaming
Source
NVIDIA GeForce 9600 GT gaming benchmarks