If all of the different RAM modules that you are considering are rated at DDR2-1066 and 5-5-5-18 and you will be running them at these specs, then the cheapest one is the best bang for the buck. Memory is the same when running at the same speed. The difference between these various modules is their respective overclocking limit and for that you would have to look at some of the head to head comparison tests. The question then becomes whether or not you want to pay extra for any differences in upper speed.