its just the CPU differences. at 1024x768, 3dmark05 is cpu limited. desktop cpus are going to be much faster than anything for notebooks, and desktop ram is also going to be better. these things will have a much larger effect on the performance than just clockspeeds.
however, when yourea gaming at 1920x1200, there wont be much differnce between a desktop and a notebook. and honestly, before you start complaining about your 3dmark scores, consider that you only had to pay 280 dollars for it, and that you can play every single game out right now at pretty much maxed settings.