Intel
http://www.intel.com/p/en_US/support/detect
nvidia
http://www.nvidia.com/Download/index.aspx?lang=en-us
nvidia is much more complicated than intel drivers, you're going to have to enter the graphics card you have. Which is not difficult, follow these guidelines.
http://www.youtube.com/watch?v=b7sBfEEEXGA
ATI
http://support.amd.com/us/gpudownload/Pages/index.aspx
ATI is the same as nvidia, you have to enter your information. So here's another guide made by someone else on how to update your graphics card.
http://www.youtube.com/watch?v=OE852DElt-c
I wish the best of luck to all, and hope you find what you're looking for.