>>2
Quad Data Rate SDRAM is the modern day RDRAM.
>>7
No one said elsewise, in fact you're just repeating what #4 already explained.
My advice would be to purchase boards that support DDR2 from henceforth but to not buy into DDR2 800. Rather you are better off buying DDR2 667 as it is cheaper than DDR 400 and theoretically the faster of the two, you can find a 2x512M kit for $60-65 w/o much effort. It is also with this that I recommend SAM2 over S939, it's just the obvious next step and I am really digging the new HSF standard AMD is putting to use on it.