Here you can see the difference between the 620 and 965BE http://www.anandtech.com/bench/Product/106?vs=102
The increase from GPU would be based on your monitor resolution but the HD5770 handles everything decent up to 1920 x 1080.
Thank you very much, very helpful.
After looking at that the difference in FPS on the games was'nt as much as adding a new card but obviously the CPU would speed up my system as a whole. Plus I would need to upgrade my PSU to Crossfire two 5770s. I shall think about this.
Thanks for the reply