I purchased a 15" Macbook Pro Unibody 2.66 Ghz last week and almost immediately had some buyer's remorse over choosing this model rather than the 17" UMBP so I searched the discussion boards to get some user opinions. The topic regarding the 17" UMBP screen observed to be dimmer than the 15" UMBP caught my particular attention. I figured the only way to put any validity to the issue was to check it out for myself. I met up with a friend who had purchased the 17" UMBP in Feb and had both comps placed side by side with the "rocks" wall paper in backdrop. It took about 30 seconds for the both of us to realize the 15" UMBP was SLIGHTLY BRIGHTER than the 17" UMBP, and that the 17" screen definitely had a BLUE overtone. You don't need to implement any mathematical calculations or use special equipment to come to this conclusion - (check out the photos and let me know what you think...) Also, something that may be difficult to detect in the attached photos, the 15" UMBP seemed to have a crisper picture. With all this, the higher res in the 17" along with the 8 hour battery life still has me debating whether or not I should exchange. 🙂