He has a GTX 560 Ti why, would you recommend he gets a GTX 480?? That's not even what he was asking.
OP what you need is a new CPU. A dual core at 3.1Ghz is what's holding you back. I would look at a Phenom II X4 965/970. The good news is that your board will support it.http://www.asus.com/Motherboards/AMD_AM3/M4A88TDM/#CPUS
Beyond that add another 4GB of RAM ( 4GB is still pretty good for gaming but some games do better with 8GB ) and maybe look to add an SSD. Those thngs are very much secondary to the CPU though.