I am fairly new to the overclocking game also, so someone please correct me if needed.
Tests have shown that USUALLY the best setting is to run a ratio of 1:1, meaning have your CPU's FSB run at the same speed of your DRAM clock. Your "system clock" is going to be your actual front side bus speed, Intel just tries to be all cool by claiming 4X the actual speed because of the QUAD PUMPED memory architecture.
You're FSB speed is 133Mhz, overclocked to 142Mhz. Try setting your DRAM speed to 142Mhz, even though it has the potential to run at 166Mhz out of sync. This would eliminate any wait states and allow you to run more aggresive memory timings.
I would set it in sync and run a benchmark, then put it at the normal settings and run the benchmarks again. Tweak until you are satisfied.