Because some boards out there such as the ASUS A7M266 have been proven to perform much better with DDR than most other DDR boards which arn't much improvement from the KT7 and other boards that use regular PC133 SDRAM. If you want to go DDR, make sure you go with a board that will take advantage of the DDR's capabilities! otherwise you might as well just go for a board with SDRAM. I'd definitely go DDR!