Just my opinion about ram… the whole frequency rating bull (DDR 400, DDR2 800, DDR3 1600) is a product of rambus marketing nonsense. DDR essentially simulates a wider buswidth, not a higher frequency.
The actual bits still take 5ns to go from on to off and vise versa in DDR 400 and DDR3 1600. In other words, the actual modules (chips) themselves still operate at 200mhz, there is just some clever interleaving of signals which, again, simulate a wider bus and not a higher frequency.
Personally, I’ve made a commitment to never buy 133mhz or 166mhz dimms. I don’t care what generation it is from (SDR, DDR3), or if the current gen of CPUs don’t have the chops to handle that kind of raw throughput yet, I’m getting 200mhz or better. I think doing otherwise is a waste of money, especially as DDR2/DDR3 ram prices continue to tick up.