I think a better question would be "should" you disable it - Probably NOT.
I Have a Samsung 711 which has the iGPU (HD3000) and a dGPU (Nvidia 540M).
The system will auto select which GPU to use, For 2D applications the Intel HD3000 is used, but if I run a 3D app (ie Furmark) it will auto switch to the 540M.
There are some encoding programs that will use BOTH at th same time.
Since the Laptop did not come with both, you may need to load a program that does the auto switching. While all my desktops use a ATI GPU, I think you will find that Nvidia has better software for use with a iGPU and dGPU.