Fsb with amd 64 x2 cpu?

OK, just needing some clarification from OC's out there: Intel uses a "real" FSB to comm. with the NB, and AMD has the memory controller embedded in the chip, correct? Are all mobo's quad-pumped now, or just amd's? I ask because I have an Athlon 64 x2 4600+ and the "FSB" is 200 x12 mult= 2.4GHz. CPUz says my mem bus is 400MHz, but my mem is DDR800. Do you get the 800MHz because it's DDR?