Simply not true. Most notebooks lag far behind in the graphic card department because most notebook users are not using them for graphics. Besides where there is speed as in a next gen graphics card there is heat and a lot of it. I've seen the fan on my video card and I'm not sure a smaller more compact version of it would even be possible given the amount of heat it would put out.
Any modern notebook will probably be able to handle anything you do as part of a computer science major... even if you do a lot of graphics projects.