Is this worth the upgrade? Would like to see better frame rates.
AMD Phenom II X4 965BE
G.SKILL Ripjaws Series 8GB
2 x XFX Radeon HD 5770 1GB DDR5 CFx
OCZ Agility 3 AGT3-25SAT3-60G- Boot
Western Digital 1 TB Caviar Green SATA Intellipower - Data
Thermaltake TR2 TRX-650M 650W
Thermaltake V5 Black Edition Mid-Tower
The 7850 would be superior. Your 965 will become a bottleneck at some point but your MB supports the FX line so you have an easy upgrade path. An 8320 and a 7850 would be a nice setup for some time at moderate resolutions.