AMD uses another manufacturing process than Intel. With their process they can't get to that speeds/frequencies. Their max is about 2.6GHz at the moment.
Then the multiplier is that 14 and 17 you see. It serves only to multiply the FSB (Front Side Bus - the highway between your CPU and chipset/graphics card/memory) speed (the 200MHz, 266MHz, 1066MHz etc.) to attain the frequency of the CPU ex. 200MHz(FSB) x 12(Multiplier) = 2400MHz actual CPU speed. And AMD use HyperTransport to actually get a FSB of 2000MHz, so the 1066Mhz FSB of Intel is not that big an advancement as you might think.
Also, AMD are not behind, they are using another strategy... They try to increase the performance per clock cycle instead of increasing the frequency. Intel actually decrease the performance per clock cycle to get to higher frequencies.
And I don't believe the Pentium4 Extreme Edition has L3 cache. I think you mean 512KB L1 cache and 2MB L2 cache. L3 cache are usually found on some motherboards to increase performance.