The newer Intel chipsets like i925, i945, and i955 allow use of memory ratios like 3:4 that will run the RAM faster for more memory bandwidth. Plus you want headroom for overclocking too. But on the other hand, as well as some of the DDR2-667 RAM overclocks, you will certainly have no problem with that speed of RAM. I would not recommend anything slower than DDR2-667 at this point in time though.