ddr2 800mhz on dual channel?

It is useful to buy ddr2 800mhz memory to be used on a dual channel intel board? Would ddr2 400mhz memory give the same result because the Intel 830 processor is limited to 800mhz FSB?

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.

This article seems to say that if you use ddr2 800 on a dual channel mobo then you effectively decrease the latency by 1/2 from 4-4-4-12 to 2-2-2-6. Is that really correct?

http://www.theinquirer.net/?article=23918