Whats the exact screen you got neil and what resolution. there are many variations, ie XGA, WXGA, WXGW+, WSXGA. WUXGA, Truelife, etc, etc, some are CCFL and not true Lcd screens, they vary in res from 1024x768 through to a silly 1920x1200, have you calibrated it????
Some of the 15 inch have 1920x1200 CCFL Truelife screens, these are hyped as the top of the range screens but are terrible, text etc is so small on a 15 inch its impossible to caption photos and the glossy truelife makes it impossible to use outdoors, these are brilliant for watching DVD's ets but no use as a mobile work platform.
Ive owned just about every configuration going and to me the best option is clearly the WXGA+ 1440x900 with matte screen