I just got back from Fry's and just purchased some Crucial RAM. The model number that I bought was CT25664AC800, but it's a different part number than the one that is recommended by crucial, which is part number CT817149. The only difference that I can tell was that the one that I purchased the CT25664AC800 is it's just a one 2GB stick per the Crucial website, but I purchased it from Fry's as a 4GB Kit (2x2GB sticks). The specs are the same but like I said per the Crucial site the one I purchased is 1 2GB stick, and the recommended kit is a 4GB kit. I don't see any difference in specs, but if somebody else sees anything different let me know before I install these into my iMac. If anyone is looking for a 4GB upgrade Fry's has the kit that I bought for 39.99 with a 10.00 rebate. 4GB kit for 29.99 is not bad at all. Thanks!!