DDR or Double Data Rate means it can transmit a signal on the up and down current that passes into the memory older Single Data Rate only transmitted on the up current. So that is how it gives you more bandwidth. Bandwidth is not really the same as speed though not to mention that most motherboards only take one kind of RAM so don't buy DDR unless your motherboard can accept it. The two types have different pin counts so DDR RAM will not physically fit into an SDRAM slot. There is also different Latency and the speed rating but that is really just a measure of what they CAN run at not what they are running at. The actual speed of the ram is determined by the motherboard bios/cpu front side bus. So if you buy 2700 or (333Mhz) ram and only run your CPU at 266Mhz FSb then your ram will only be running at 2100 (266Mhz). Just some things to consider, its not really just a matter of speed.