I am considering getting some more RAM for my new 15" MBP. I would like 8 GB but I am just not sure if it is worth it. I do a lot of Photoshop, Aperture, Illustrator and games. I would like to run Parallels more also, but I hate taking that much of a hit in memory (hence the upgrade). Should I go for 8 or is 6 enough? Also, I have heard about "trade in" programs. can some one tell me a little bit more about that?