With AMD you should be able to gain some additional speed by
overclocking.
If you are not familiar with this approach, but would like to try I
would suggest you limit any such mod. to 5%. I have used both types
of chip and the one Michael refers to are chips that have
Hyperthreading, and they work extremely well, if you can make use of
the extra thread per core.
In general AMD give a faster return for commensurate CPU's, but this
is very muddy water and requires considerable research plus T. & E.
with O/Cing.
Ant.