Re: New mobo + old ram question
It only has 4 slots, so as long as you fill it up homogeneously (all 667's, no 800/667 mismatching), I think its possible to clock them to 800. I wouldn't recommend any higher for RAM that runs at 667 in stock speeds. 1066 isn't necessary anyway, unless you have a QX9650 (and even then, its only to keep up with the CPU's FSB).
I cannot guarantee this as i've never used Gigabyte motherboards for overclocking RAM.