Perhaps because even if the program is not MP aware the Core 2 may still be the fastest processor. The Prime95 program used in the benchmark results I linked to does not support processor parallelism; the results are from a single core. That said, Prime95 includes lots of hand optimized assembly language FFT routines, so it might not be the best benchmark for non-optimized applications.Even without the application being MP aware, you can pick up some speed from Windows using the other core for housekeeping. Unless there is a compelling reason not to consider multi-core processors, I am at a loss as to why you won't consider such a processor.
Not exactly what you are looking for, but good for relative ranking.