The first one is correct. However if your ram wasn't running in dual channel, Id be inclined to say #2 is correct also. Although I don't completely agree with it, when you run your ram in dual channel, you 'effectively' double your dram speed.
Eg.
800Mhz ram in dual channel: 800/2 = 400Mhz
800Mhz ram not in dual channel: 800/4 = 200Mhz
Im pretty sure I'm right, but by all means if it isn't right can someone please say something.
Chris
Dual channel does not double the speed, it only "theoretically" doubles the bandwidth. Think of a four-lane highway (single channel) vs an eight-lane highway (dual channel).