That Phenom 9750 probably got good a nice useful life span if you got it when it was fairly new, but you don't mention if you have it overclocked at all.
I don't know why nobody has responded yet but you should be able to stick in a Phenom II, or Athlon II CPU and see improvement. Personally I would not go less than Phenom II because you can find them for the same price as the Athlon II chips these days.
Your GPU is still great for gaming, you probably wont be able to max every new game 1080P but you should be very close and all older games should play like a breeze.
Upgrade to a high clocked Phenom II and you will see great gains esp. if your current Phenom is not overclocked and running at stock 2.4GHz.