tommy98789 i think you have your info mixed up. i checked the mobo specs and it does support DDR400 pc3200. the AGP bus, CPU bus, and memory bus run at different speeds. you do not have to synch them to have your computer running. although that would be good to have your CPU and memory front side bus to be the same speeds, you do not have to.
so to answer your question yes you can do that by setting the memory from 200mhz or by SPD default setting to 166mhz. but again you do not have to do this. your computer will run at all the defaulted settings, theres nothing you should have to change.