NVIDIA GeForce gt 620 M and Intel graphics card conflict in ubuntu 12.04?

I have NVIDIA GeForce GT 620M in a laptop (32-bit system) with Intel Graphics card, when I’ve tried to install the NVIDIA driver and CUDA GPU computing toolkit in ubuntu 12.04 in different ways it destroyed my system, I’m not sure if the problem was the conflict between the 2 drivers or my installation steps!
My question is: what is the best linux distribution(s) (and its version) that has a stable version of NVIDIA driver that works well with other graphics cards, keeping in mind that I have already Windows 7 installed in the same laptop? and what are the correct steps to install NVIDIA Driver and CUDA GPUU computing toolkit?