Lets just say even the e6300 when OC'ed to easily reachable speeds still beats amd's $850 processor on just about every test. And the e6600 at stocks speeds easily whoops it. Its almost impossible to compare, you would be absolutely shocked how much faster your comp is.
Thats why I also compared the non-oc'ed 6600 to it, just saying a $180 cpu that is at speeds just about anyone can hit with it beats a $800cpu.that is just f you assume the AMD isnt overclocked. but yes, the duo's are really good CPU's