I have a first gen white macbook, a 2.33 core 2 duo 15" macbook pro, and a 15" aluminum powerbook g4. the macbook's max volume is significantly lower than the macbook pro and powerbook. when watching video files that tend to have lower sound mixes, i'm fine with the powerbook/macbook pro, but with the macbook i usually have to attach external speakers or i have trouble hearing everything unless i'm in a dead silent environment.