its all the same stuff - just marketing
here is the important facts on ram:
1) 4 sticks often have issues to do limitation in the bus bandwidth - if you want 4 gb use 2 sticks
2) most memoy is 5-5-5-15 ddr800 1.8v - if it says 4-4-3-8 you need to manually set it. even kingston pc10000 ddr1200 will boot at ddr800 and cpuz will read it as such - you need to manually set 2.3v (in the case of ddr1200) and you latencys and fsb
3) lower latencys are faster then higher speed
1066 chip with 1066 ram 5-5-5-15 will be slower then a 1066 chip at fsb1500 and 750 memory at 4-4-3-8 - the memory bandwidth will be close but in most cases the ddr800-850 4-4-3-9 settings are the best with the good micron chips
you should tune your system for 1:1 or 1:2 then check the memory bandwidth with sandra
thats why i build fast computers!