Hi folks. I'm looking at the RAM configs on the new 27. I'm getting 8GB,and 4x2GB is alot cheaper. Is this because a) Cheaper individual parts b) not matched pairs? If there is no performance difference, then I'm happy to get the 4x2GB. I'd only be upgrading to 16GB and thats a long way away. Also, just being lazy, will any 3.5" HDD fit into the iMac? I was thinking of getting a different HD and replacing it myself. Shame there is no way of having two HDD's in there. Thanks advance!