There can be various levels of quality in DIMMs that are made with Micron memory chips. Although the chips themselves will be high quality, the rest of the DIMM can be substandard. It all depends on the manufacturer of the DIMM. The current specs that govern the manufacture of memory (PC100 or PC133) specify many more requirements than the speed of the chips themselves. On the other hand, Crucial is the retail arm of Micron. They manufacture the whole DIMM and everything is high quality. They give a lifetime warranty as well as a compatibility guaranty. In my opinion, it is worth the little extra to get it direct from the manufacturer.