Proprietary drivers

Hello I am wondering how should i install proprietary drivers on mainline kernel. I have NVIDIA Corporation G98M [GeForce 9300M GS] graphic chipset and Broadcom Corporation BCM4312 network adapter. in Broadcom case the driver source is available although the compilation process is not very clear to me but nvidia source code is not available and i don't know if there is a way to use drivers available in ubuntu's repository. My linux distribution is Ubuntu 14.04 and when i install mainline kernel these two hardware stop working. And also how can i find linux certified laptop. i mean a laptop that has all its driver in linux source tree. i have seen ubuntu certified laptops that again use nvidia chipsets. thank you