DDR2- go up to 1000mhz (most miobos support 533mhz or the one above)spped where as DDR curently goes up to about 533MHZ but most mobos only support up to 400mhz, DDR2 has 240 slot where as DDR has 184 slot. In performance at the moment its not that great a deal a bit like agp and pci-e in the early days not much of a differmce but soon ai believe there will be a bit of a differnce.
