AnandTech takes a look at high-speed DDR2 memory from Crucial and Buffalo:
Two trends are clear in today's DDR2 memory. First, memory speed is rising, and second, memory timings are getting tighter. When DDR2 was first introduced you were hard-pressed to find a module with tighter timings than 5-5-5. Today we are even seeing DDR2-800 that can run as fast as 3-3-3 timings, and some DDR2-533 memory, which is 1:1 with the 1067 quad-pumped bus of Intel Core 2 duo, can commonly operate at 3-2-2 timings with additional voltage. DDR2 is getting cheaper, faster, and with tighter timings.