Dual Channel DDR

Maybe I'm just missing a FAQ somewhere, but my understanding of DDR is that it needs to be 400MHz 3200 DDR. I'm probably just misunderstanding this, but can you use faster DDR for doing this thing with 800MHz FSB motherboards?

If you are talking about an Intel P4C, then you need two ddr400 sticks running in dual channel to run in sync with the 800 mhz FSB. The fastest offical ddr speed is ddr400, and it will probably stay that way until ddr-2 comes out.