I have a AMD Phenom II X4 3.2ghz quad core processor. However, Fallout 3 only uses dual core...how much of a difference would getting a stronger dual core processor make in terms of performance?

I'm not that nitpicky about it, but I use MMM, Travelers, and Wasteland Patrols (with the parameters set very high) and I want to see if it's possible to make this an entirely lag-free event with the right system specs.

Thanks in advance.

Well I use the AMD Phenom IIx4 955 overclocked to 4Ghz. But even at 3.2Ghz it is a great CPU. There really is no need to get a new CPU, especially downgrading to a dual core CPU. Because even if the game doesnt use more then 2 cores, Windows will manage the background processes on the other cores if necessary. Those mods are pretty resource intensive, what GPU do you use? Also there is no way to eliminate the lag completely without buying a Solid State Drive. Mechanical hard drives are much slower when loading everything.