I just got off the phone with AppleCare and they are going to replace the bottom and top casings of my white macbook which I purchased in Dec of 2006. The bottom white "casing" is being replaced cause of cracking marks around the back perimeter and they've admitted this is a known issue. They are then replacing the top white casing, you know with the see through "light me up" apple logo due to odd discoloration at certain spots on that casing. The discoloration is an issue Apple has gladly replaced already 2 times for me, oddly enough... ...but through browsing on the apple site and macrumors, It seems that the new white macbooks are made of plastic...and am therefore guessing the old ones aren't? If this is the case, will my white macbook come looking/feeling different?