The architecture argument is perfectly valid, and there is an easy enough way to see which system is faster through running benchmarks.
If
Wolfram and
amirp wouldn't mind, I'd like to see how your systems do running the benchmark application that is on the overclocking company's page. I downloaded it and ran it, it's basically a DOS console type app, but it is complied for use with 64-bit hardware.
You can read all about it (single threaded, 64-bit, requires 1 GB to run, will create a "report.txt" file when it's done, makes a whole bunch of other smaller files as it runs which you can throw out).
http://www.liquidnitrogenoverclocking.com/benchmark_results.shtml#page_top
The top reported speed was by an Intel Xeon W3580 @ 4.95 GHz, and the running time was 3 hours, 12 min, 40 seconds.
My own time was much, much longer (5 hours+) but I am running it on an old machine.
I'd like to know what your system at 4.0 GHz can do, versus what the performance of the systems for sale can do.