If you're already running a 775 platform, you can also consider the
or q9550 if you live near a microcenter for the same cost or less. Being DDR2 ram, that is going to be the sticking point to a high OC especially if its 800mhz. You should still do well though.
Are you lacking in performance that a 3.7ghz C2D isn't cutting it? If its just CPU envy, I'd wait and save for the i5 750 and do a full platform upgrade.