I am surprised to see your CPU only running at 2.0GHz since dual graphics cards are bottlenecked by slow CPUs. Frankly, I don't know why Intel and AMD decided to screw things up and confuse people by releasing such slow quad cores in the consumer market. Quads running at 1.8GHz, 2.0GHz, etc. are meant for servers.
A lot of software for the desktop/laptop market tends to be poorly optimized for multiple cores, and usually distribute tasks unevenly. Having a quad doesn't help much if the software is placing most of the load on only one or two cores. It basically turns your CPU into a 2.0GHz dual core, which sucked in 2005 and sucks now.