You need DDR2, 240 pin, non-ECC, non-buffered modules. The certified list doesn't have anything to do with certifying brands based on their type, it has to do with certifying that they've been tested and are compatible. Even if you get the exact right type of memory based on the specifications, there's no guarantee it will be compatible. Right now a lot of boards seem to have issues with certain memory modules, and the M2N-E seems to be one of them; lots of modules that ought to work just don't. It might be safer to pay a few bucks more for one that is certified. Or if you can find one of the rare reviews of the board, see what modules they tested with. Or if the vendor has a good return policy and will let you send it back for free if it just isn't compatible, you only lose time and some shipping costs.