You need at least (IMO) an i7 cpu series to run those new games without any problem. Your Motherboard is also a bit old so I don't think it supports that CPU.
The i5 2500k is currently the defacto standard that most people recommend (the 3750k Ivy Bridge is around the same ballpark as the 2500k but if you have a dedicated GPU already, you won't notice much improvement at all). The most important piece of hardware for gaming is the GPU, not the CPU.
You will need a motherboard that has an LGA 1155 socket to perform this CPU upgrade.
[Edited by Neo7, 11/22/2012 10:14:19 AM]
Yeah, sure you need a better GPU, But on latios case, he should buy a good CPU as well. This is why I talked about CPU only.
Also I said i7 because a better and higher stuff can work for a much long time. Consider that new things are coming to the market everyday and being updated monthly. So if you go for an i7 one, you can keep it for a long time, but i5 supports your needs just for a couple of years.