The Sims issue could also be a GPU card issue as well. You should try Scan UK for RAM, I bought 4x4GB Corsair Vengance low profile from there for about £52. Good deal! Also an SSD would sort out load times as well.
Also why would the Sims be a GPU issue? I've got a 6870 in there.
Also why would the Sims be a GPU issue? I've got a 6870 in there.