I think the strategy is not right
If the video card still works you would gain more from upgrading to a new FM2 motherboard + some quad FM2 APU/CPU.Sell what you have add the money for the new video card and switch to USB 3.0 ,SATA 3 ,PCI-E 2.1 and so on in a blink of an eye.
This is why :
-Getting a new video card that will be fed with data by that lazy CPU will mean no gains of performance.
-DDR 2 is outdated and slower that DDR 3 and not cheaper
-FM 2 uses less power
-FM 2 is a socket that will last so you can upgrade to a better APU if needed in the next years.
On short don t be surprised if by upgrading to a new video card and more DDR 2 RAM you will only waste money with no substantial increase in performance ,with the risk of the new card not to work.
If you add more sticks of DDR 2 RAM you will also notice a drop in memory frequency (due to the lazy IMC in the Phenom) which will make the more amount of RAM useless as well