It's more like 2 trucks that go 60 MPH on the highway vs. a single truck.

If your load fits across the 2 trucks then you get the benefit but the load is delivered in the same time.

Where this mostly pays off is Vista since it will rev up many programs just in it's "OS" and you'll need one for the OS and one for your application.

Also where dual core shines is video editing and rendering. That's a big load and just like the trucks almost all video editors will use the added payload capacity.

Bob