My Desktop Graphics and Laptop graphics differ with the desktop Having a GTX460 and a Dell s2209w monitor and the colours are crisper and the lappy is a HP Compaq NX6325 with standerd TFT monitor having a lower colour output as it has a Radeon Xpress, You can see a big differance in the two, Just as what kemical said it's just normal an nothing to worry about, It just the Graphics card not the operating system. Just check for updated drivers anyway.
Edit:, It (the difference) would been there when you had Windows 2000 or windows XP, and you didn't really notice, But it would come apparent with Windows Vista or Windows 7 Because of the Aero, and eyecandy thats on these Os's