that series of processor weren't the best over clocker's, and when you do over clock them you put more stress on it than the benefit you will receive. next to nothing.
if you insist on over clocking..... get the fastest memory your board can support, ( 2 sticks only ), lower the multiplier on the processor and work on getting the memory to run faster. again, gains will be minimal.
and seeing how you don't have a second machine, or can build a new one right away, I would leave well enough alone before you end up with nothing.