Woodcrest Or CloverTown? When In This Example Price Is Pretty Much The Same

When it comes to CPUs I am pretty clueless, so excuse any silly comments here.

I am little confused by the performance benefits vs price of quad core and duale core processors. I am hoping some of you experts can clarify this for me.

For example, on newegg they have the following:

Intel Xeon 5160 Woodcrest 3.0GHz for $877

and the

Intel Xeon E5345 Clovertown 2.33GHz for $879

Now though the Clovertown has a lower processing speed, I get to run 4 processes simultaneously and have an aggregate total processing power of 9.32 ghz.

On the other hand, the Woodcrest proc allows me to run 2 processes simultaneously and I have an aggregate total processing power of 6 ghz.

Now I am probably reading this wrong, but why would you purchase the woodcrest when the price is essentially the same and benefits are much greater?

On a last note, do programs such as mysql and apache 1.3 take advantage of the multiprocessors?