in terms of sheer clock speed then the 3 GHz core 2 duo would win
BUT
in terms of sheer volume that the cpu can accomplish in a given amount of time
then its the 2 GHz core 2 quad
BUT
thats IF both cpus are given the same amount of work to accomplish
the clock speed wont me squat if you have a low RPM HDD, or an insufficient amount of RAM
there are other things that come into play as well
your better off telling us what you are trying to do
now if you really want the best
then get an i7 and be amazed (quad core with Hyper-threading)
in other words it works like 8 cores instead of just 2
BTW dude 56013
you have more patience then i do