there's been a lot of problems with ddr400 ram, I personally got mine today to 13.5* and 190FSB that works out to be 2565Mhz ladies and gentlemen this is a 800mhz OC on a Barton 2500.
Aslong as you can change the multiplier you can run whatever FSB the memory and motherboard support, if thats 200mhz then 200mhz is what you can run at