Just picked one up used and would like to upgrade the RAM. I've read I can upgrade it to 6GB but because RAM isn't packaged in a set of two 3gb sticks I'm wondering if I can pick up two 4gb sticks and even though two of those gb will go to waste or if that will cause problems. Looking for package 4gb+2gb deals on ebay comes with serious markup. I paid the same price for 16gb ram as a couple vendors are trying to pull for 6gb.