Which is a Better Gaming PC between this??

Gpu- Radeon 5770
Cpu- AMD Phenom II X4 955(QUAD CORE)
Ram- 4GB DDR3

OR

Gpu-Radeon HD 6870
Cpu- AMD Phenom II X2 655(DUAL CORE)
Ram- 4GB DDR3

I'll be playing games like GTA 4, Crysis 2, Just Cause 2, Black Ops, Far Cry 2, Metro 2033, Mafia 2.

At -
1440*786 resolution.(am not going to change it)

Thanks.