Hi, I've got a mid-2009 13" Macbook Pro and am thinking about upgrade the ram as I've found my page outs gets quite excessive and system slows down when working on CAD/Matlab with the rest of my things open (I have a second screen with iTunes/Mail etc running 24/7). I currently have 2GB and I've found on Crucial that I can get 1 x 4GB of ram for about the same as 2x 2GB of ram. ±£3/4 So upgrading to 4GB or 6GB for the same price. Does loosing dual-channel have that much of an influence if i'm gaining 2 extra GB's? I'm keeping one eye on upgrading to 8GB in the future but can't afford to at the moment. Also will upgrading, in say, 6 months/1 year to 8GB by adding another 4GB cause any problems so long as I buy from crucial again? I've heard that it is best to buy them in sets so they are identical. Thanks.