I use an msi board; to get a safe overclock, drop the ram setting a notch; for pc6400, I use the ratio 1:1.66 or set it at 667. For the cpu fsb, I use 240 to get a 20% overclock. I don't try for any more as I've had problems with my pci lock, and the dsl modem crashes.
That's a socket 754 CPU right? I don't remember if there were 939 or AM2 versions of it. Anyway, if you don't have overclocking RAM, then lower the speed of the RAM, loosen the timings, and slowly increase the FSB. As o1die said though, going too far on the FSB can have stability issues depending on the board. This is more common on older boards than newer ones.