Shaders and VBOs are the future.  That's why they're so highly advocated.  That doesn't mean the old ways are wrong; on the contrary, they're excellent for whipping up a quick demo.  Don't even worry about OpenGL 3.0 or 3.1.  PyOpenGL versions for these, as far as I know, don't even exist yet. 

Both shaders and VBOs are widely supported, particularly on nVidia hardware.  Shaders, for instance, go back a long ways.  You'll probably want shader model 1.2 or 1.3.  Both run on my old laptop (nVidia 7600).  If you want to use shader model 1.1, you can use really old hardware.  Wikipedia says the 4xxx series supported it.

If you're just going for data visualization, though, you may not even need shaders.  Likewise, a simple display list is usually just as fast as a VBO. 

I do definitely recommend learning how to use shaders at least at some point, however.