DDR2 1066 vs 1200

a. I get lost a bit with newer intel CPUs. Correct me if im wrong, DDR2-1066 uses 266Mhz chip, while 1200 uses 300Mhz. Therefore, if you are buying q9550, both would need to be overclocked?.. since the bus multiplier is 8.5x333 = 2.83Ghz.
b. If both RAM can be used for q9550 w/o overclocking, would it give performance increase using DDR2 1200 instead of 1066?

TIA for the feedback

Actually, DDR is double data rate. Therefore, 1066 is 533MHz base clock rate, and 1200 is 600MHz. Both are higher than needed on a Q9550, which actually needs more like DDR2-667 or DDR2-800 (probably the best choice, as DDR2-800 would allow for a 1:1 ratio with a 1600MHz FSB, which would be an overclock to 3.4GHz). 1066 would allow for a 1:1 ratio all the way up to a 2132MHz FSB, which is an overclock to over 4.5GHz.