it makes no sense to up your CPU FSB to 200mhz if your memory is running at a slower 166mhz. running the CPU and memory out of sync is pretty much poinless becuase one cannot take advantage of the other's increased FSB.
if you set cpu external freq you should reduce your cpu multiplier or risk CPU overheating or at worst, it could fry that cpu.
i strongly suggest you leave all those settings alone unless you use only pc3200 in the system.
this is useful: