To up the FSB is the easier way to do so, and also would give your whole system better performance since you are not only overclocking your CPU (as you would if you only set to 12x mult). but also your RAM, PCIs, etc.
You have a good system there, good mem, mobo, and cooling; I'm pretty sure your system can hit 1700mhz or more. My XP1700+ runs perfectly at 1727mhz (11x157) and I don't have such good cooling and memory as you do.