Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
There is such a thing as pc2-5400 ram. It will work fine in a macbook, but it wouldn't run any faster than pc2-5300. Your paying more for speed you can't take advantage of.
 
some brands call their ddr2-667 pc2-5400, even though ACTUAL pc2-5400 runs at 675mhz. that stuff'll work fine
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.